By John Boyd
Youtube link: https://www.youtube.com/playlist?list=PL4pmLxkc7CTcukIlpD0UThT7Y_K09oxXe
Note: This is a work in progress. These notes were hastily taken while listening to the brief linked above. I have also since found a better version of this brief that is part of the larger “Discourse on Winning and Losing”
variety/rapidity/harmony/initiative – key qualities that permit one to shape and adapt to changing env.
Sun Tzu
– Subdue enemy without fighting, avoid protracted war. All war is based upon deception. Fluidity in action. Shape enemies perception. Attack plans, then alliances, then army, finally city. Employ Cheng and chi (expected and unexpected). Use cheng to expose weakness then chi to attack that weakness. (morally, mentally, and physically) Ideally win without fighting or at least avoid protracted war.
Attack enemy plans as best policy. Dont have plans? Get inside system, understand what they are going to do. Begin to shape him and he starts drawing up plans that are no longer useful to the unfolding situation.
Alliances – split him up and then use a large fraction of your strength against a small fraction of his
Army – Do the other two first so when you do do this they become unglued.
“He who prepares or reinforces everywhere is everywhere weak” Sun Tzu
Savkin- Unequal distribution of forces across a front to concentrate forces for main attack at decisive point. Also Sun Tzu – flowing water
Use combined arms for cheng and chi tactics. They play off eachother.
Clausewitz
book 8 – 4 exceptions to concept of concentration, none to speed. Premier idea must be speed then. Looking at exceptions if you operate at a higher tempo then you dont have to abide by concentration.
OODA loop not only about speed. “You can go fast right over a cliff.” Its about relative speed. You dont have to go faster if you can instead slow them down.
Ambiguity may be even more important than deception.
Napoleon
– Intel/recon to eliminate or confirm hypotheses about enemy to reduce uncertainty and simplify own plans as well as uncover enemy plans and intentions.
– Cloak/mask own movements.
– Expand and contrast forces irregularly and rapidly to cloud/distort maneuvers but also focus effort at the decisive point.
– Attack enemy at outset with changing moves and diversions in order to upset his actions and plans to unbalance them.
Clausewitz
– Uncertainty acts as an impediment to vigorous activity.
– Friction impedes activity. “only difference between real war and war on paper”.
– Exhaust enemy by influencing them to increase their expenditure of effort
– Focus all efforts vs enemy center of gravity. Trying to reduce own internal friction
– He overemphasized decisive battle and under emphasized strategic maneuver
– Failed to address idea of magnifying enemy friction/uncertainty
– Failed to develop idea of generating many non-cooperative centers of gravity by striking at those vulnerable yet critical connections that permit larger system to exist
– Did not see that many non-cooperative centers of gravity paralyze enemy by denying them opportunity to operate in directed fashion, hence impede vigorous activity and magnify friction
Jomini
– Mass vs weakness
– Preoccupied with formations and formal orders/arrangemnets
– Lacked appreciation for use of loose/irregular swarms of guerrillas to mask own activities/intentions
– Result: operations become stereotyped
All 3 had same blind spot. Did not appreciate loose/irregular tactical arrangements/activities to distort own presence and intentions as well as confuse enemy operations.
Viewed operations from the top down– emphasizing adaptability at the top and regularity at the bottom. (Product of their ideology of that time)
If you use ideology as a screening device you are denying yourself the ability to see things from a different perspective.
These tactics minimized the possibility of exploiting ambiguity, deception, and mobility to generate surprise for a decisive edge.
Evolution of tactics did not keep pace with increased weapons lethality developed and produced by 19th century tech
WWI
– Schlieffen plan – large scale single envelopment scheme
– Even advance to protect flanks, reserves provided when attack held up at points of strong resistance. Mass v mass. Developed fortified terrain to pin down attacker.
– Result: stagnation and enormous attrition
*****Start of Part 7 Video*****
My notes become much more detailed and wordy, sorry..
– Prep attack with arty, enemy send reinforcements to that area, disperses frontline
– Enemy intel notices buildup of arty ammo
– Capt Andre Laffargue (French) and Gen von Hutier/Ludendorff – Infiltration Tactics
– TE Lawrence and Paul von Lettow-Vorbeck (Prussian) – Guerrilla Tactics
Infiltration Tactics
– Short but intense arty w/ smoke to disrupt and obscure
– Stosstruppen (small squads of thrust troops) thrust forward behind rolling arty w/o any “effort to maintain a uniform rate of advance”. They seep or flow into any gaps/weaknesses they find
– Kampfgruppen (small battle groups) follow to cave in exposed flanks
– Reserves and stronger follow-ons move through to maintain momentum and exploit success as well as attack flanks and rear to widen penetration and consolidate gains vs counter attack
– Idea: Hurl strength (in depth) via an irruption of many thrusts, thru weaknesses along many paths of least resistance to gain opportunity for breakthrough and envelopment. i.e. It took them till WW1 to realize what Sun Tzu wrote in BC
– Key Point: Fire at all levels and together. Gas and smoke (as well as fog or mist) represents immediate/ominous threat to capture enemy attention and obscure view of infiltrator movements. Dispersed and irregular character of moving swarms permit us to blend against irregular and changing terrain features. Taken together, the captured attention, obscured view, and indistinct character of moving swarms deny adversary opportunity to picture what is happening
– Result: Infiltrators appear to suddenly loom-up out of nowhere and blow thru, around, and behind disoriented defenders
– Essence: Cloud/distort signature, improve mobility to avoid fire yet focus effort
– Intent: Tactical dispersion in a focused way to gain tactical success and expand into a grand tactical success
– Implication: Opposite of “Principle of Concentration”. Penetrate adversary to generate many non-cooperative or isolated centers of gravity as basis to magnify friction, paralyze effort, and bring about adversary collapse.
– Infiltration tactics gave ability to evolve effective tactical versions of Napoleon’s multi-thrust strategic penetration maneuvers that could offset the massive increase in weapon lethality developed during the time period
– WHY: Top-down command/control system, addition to Principle of Concentration and drill regulation mindset taken together reveal an obsession for control by high-level superiors over low level subordinates that restrict any imagination, initiative, and adaptability needed by a system to evolve the indistinct-irregular-mobile tactics needed.
– “If you can penetrate their stability or system, why should they quit? They won’t.”
– ***”Terrain doesnt fight wars, machines don’t fight wars, its people who use their minds”***
– Use terrain as a medium for maneuver. Elastic zone defense, give up terrain to draw enemy beyond their support then collapse them with arty and flank attacks.
Guerrilla Tactics
– Gain support of population. Must “arrange the minds” of friend, foe, neutral alike. Must “get inside their minds”
– Must “be an idea or thing invulnerable, without front or back” (inconspicuousness and fluidity of action)
– Tactics “should be tip-and-run” with “use of smallest force in quickest time at farthest place”
– War of detachment using mobility/fluidity and environmental background as basis for “never affording a target” and “never on the defensive”
– Idea: Disintegrate existing regimes ability to govern
– “like the Mongols, be everywhere but nowhere”
– TE Lawrence wanted to draw in forces, he was the Cheng
– Moving backwards isnt always defensive, its based on who has the initiative (see elastic zone defense above). If you have the initiative it doesnt matter which way you move. Initiative is who is inside the others OODA loop.
– Impression: seem to be similar in nature to infiltration tactics
Soviet Revolutionary Strategy
– exploit idea of crises and vanguards
– Result: a scheme that emphasizes moral/psychological factors as basis to destroy a regime from within
– Select “the moment for the decisive blow … to coincide with the moment when the crisis has reached its climax …” – Lenin
– Goal: Destroy capitalism as well as its offspring imperialism and replace it with a dictatorship of the proletariat
Guerrilla War
– Mao synthesized Sun Tzu’s ideas and Napoleonic style under umbrella of Soviet revolutionary ideas to create powerful way for waging modern (guerrilla) war
– Result: Modern guerrilla war has become overall political, economic, social, and military framework for “total war”
Blitzkrieg
-Infiltration tactics mated with new tech (tank, motorized, better comms, tactical aircraft) by Fuller and Guderian
-Result: Blitzkrieg to generate a breakthrough
– Action
– – ISR to probe and test adversary before/during ops to uncover and shape changing patterns of strengths/weaknesses/moves/intentions
– – Those patterns and changes are weighed against our situation to expose attractive/appropriate alternatives that exploit adversary vulnerabilities/weakness. Help shape mission commitment and influence intent.
– – Schwerpunkt (focus of main effort) established before and shifted during combat ops to bypass adversary strength and strike at weakness. Nebenpunkte (other related or supporting efforts) employed to tie-up, focus or drain away adversary attention and strength elsewhere
– – Special teams infultrate enemy rear areas where they seize vital areas, sever comms, destroy vital areas, and sow confusion/disorder via “false messages and fake orders”
– – Firepower (air and arty) focused to impede (or channel) adversary movement, disrupt comms, suppress forward defensive fires, obscure advance, divert attention
– – Armored recon, leading armored columns, advance rapidly from least expected regions and infiltrate adversary front to find paths of least resistance
– – Assault teams work together to quickly open breaches found
– – When breakthrough occurs, independent ready teams penetrate at high speed deep into adversary interior to cut lines of comm, disrupt movement, paralyze command and envelop adversary forces
– – Motor/foot infantry further back pour-in to collapse isolated pockets of resistance and widen the breaches
– Idea: Conquer and entire region in the quickest possible time by gaining initial surprise and exploiting the fast tempo/fluidity-of-action of armored teams /w air support as basis to repeatedly penetrate/splinter/envelop/wipe-out disconnected remnants of adversary in order to confuse, disorder and shatter their will to fight/resist
– Impression: Generates many non-cooperative centers of gravity as well as undermines or seizes those that adversary depends upon in order to impede activity and magnify friction
– How do they do this without losing cohesion?
Blitz Operating Philosophy
– Key Point: each level has their own OODA loops. The more events we must consider, the more time it takes to cycle through OODA.
– Idea: Faster tempo at lower levels should work within the slower tempo but larger pattern at higher levels so the system does not lose cohesion
– How do blitzers harmonize differing tempos?
– Give lower-level commanders wide freedom *within an overall mind-time-space scheme* to shape/direct their own activities so they can exploit tempo at tactical yet be in harmony with larger pattern associated with the more general aim at the strategic level
– Shape overall scheme by using mission concept or sense of mission to fix responsibility and shape commitment at all levels. Use Schwerpunkt concept through all levels to link differing rhythms so each part can operate at its own natural rhythm
Blitz and Guerrilla
– Probe and test adversary (and any allies) in order to unmask strengths, weaknesses, maneuvers, and intentions
– Exploit critical differences of opinion, internal contradictions, frictions, obsessions, etc. in order to foment mistrust, sow discord and shape both adversary’s and allies perception of the world
– – This creates atmosphere of mental confusion, manipulates/undermines adversary plans/actions, makes it difficult for allies to aid adversary
– Purpose: Force capitulation when combined with external political, economic, and military pressures OR weaken foe to minimize his resistance against military blows to follow
– Mind-Time-Space Scheme: a common outlook based on professional officers who had the same training/education/way of thinking/speech and who allows the subordinate a very great measure of freedom of action and freedom in the manner of executing orders
– – Without a common outlook superiors cannot give subordinates freedom-of-action and maintain coherency of ongoing action
– Mission: Contract between superior and subordinate. Subordinate agrees to make actions serve superiors intent in terms of *what* is to be accomplished while superior agrees to give subordinate wide freedom to exercise imagination and initiative in terms of *how* intent is to be realized
Schwerpunkt
– Acts as center or harmonizing agent that is used to help shape commitment and convey or carry out intent at all levels
– Image around which maneuver of all elements are focused to exploit opportunities and maintain tempo of ops and initiative of many subordinates is harmonized with superior intent
– A focusing agent that naturally produces an unequal distribution of effort as basis to generate superiority in some sectors by thinning out others
– A medium to realize superior intent without impeding initiative of many subordinates
– Represents a unifying concept that provides a way to rapidly shape focus and direction of effort, thereby permit a true decentralization of tactical command within centralized strategic guidance without losing cohesion of overall effort
– Represents unifying medium to diminish friction and compress time in order to generate favorable mismatch in time/ability to shape and adapt to unfolding circumstances
German Operational Philosophy
– Emphasized *implicit over explicit* communication
– Need a common outlook to understand each other
– Need trust in commanders
Modern Guerrilla Campaign
– Action
– – Capitalize on discontent and mistrust
– – Set up admin and military org and comms network under guerrilla leadership without arousing intel/security apparatus
– – Exploit subversion of government and conversion of people to guerrilla cause
– – Shape propaganda, foment civil disorders, use selected terrorism/sabotage and exploit resulting misinformation to expand mistrust and sow discord
– – Employ tiny bands for surprise hit-and-run raids, disperse/scatter those bands to spread out government forces while larger bands take out the dispersed forces
– – Play upon grievances and obsessions of people and encourage government to indiscriminately take harsh reprisal measures against them
– – Demonstrate disintegration of regime by striking cheng/ch’i fashion
-Idea: Defeat existing regime politically by showing they have neither the moral right nor demonstrated ability to govern and militarily by continuously using stealth/fast-tempo/fluidity-of-action and cohesion as a basis to harass, confuse and ultimately destroy the will or capacity to fight
– Know the adversary, know yourself, AND know the uncommitted 3rd party
– Essence: Capitalize on corruption/injustice/incompetence to generate mistrust and discord SIMULTANEOUSLY share existing burdens with people and work with them to root out and punish corruption, remove injustice, eliminate grievances to form bonds between people and guerrillas
– Intent: Shape and exploit crises environment that permits guerrilla vanguards to pump-up guerrilla resolve, attract uncommitted, and drain adversary resolve
– Implication: by being able to penetrate essence of adversary’s moral-mental-physical being, generate many non-cooperative centers of gravity, as well as subvert those centers that adversary regime must depend upon, in order to magnify friction, paralyze, and bring about collapse. Yet, guerrillas shape moral-mental-physical atmosphere so potential adversaries as well as uncommitted are drawn towards their philosophy and are empathetic towards their success
– Increase friction in regime, help people/3rd party uncommitted
– Insight: Revolution becomes ripe when many perceive an illegitimate inequality.
– Guerrillas not only need illegitimate inequality but they also need support of the people
– Guerrillas must become indistinguishable (feelings/aspirations/goals) from people while government is isolated from people
– Cause government to alienate itself from the people
Read Liddel Heart and J.F.C Fuller’s books
How can we counter this?
– Key point: Difficult to sustain fast tempo AND maintain cohesion when forced to repeatedly and rapidly shift concentration of strength against weakness
Counter Blitz
– Posture
– – Emphasize ISR and set up screen of forward outposts/patrols to report on adversary activity and warn of incursions
– – Deploy, disperse, and redeploy/redisperse recon and mobile teams together with arty so they can mask dispositions as well as move inconspicuously/quickly to focus and shift local main efforts against adversary thrusts
– – Place armored teams as mobile reserve in echelon behind troops and arty so they can easily focus effort and quickly move-in to decapitate any local breakthrough
– Action
– – Employ air and fast moving recon teams to determine direction/strength of thrusts and to continuously harass by repeated delaying actions and hit-and-run attacks in order to slow momentum and erode cohesion of blitz
– – Hit adversary thrusts and resupply efforts with ambuscades and repeated sudden/sharp flank and rear counter-thrusts to channel as well as drain-away momentum and break up cohesion
– – Concentrate swift armored forces (reserve) and use with air to rapidly drive a shallow or deep flank counter stroke in order to swing in behind and roll-up blitz offensive in detail
– Idea: Smash blitz offensive by inconspicuously using fast-tempo/fluidity-of-action and cohesion of counter-blitz combat teams as basis for shifting of forces and quick focus of air and ground effort to throttle momentum, shatter cohesion, and envelop blitz in order to destroy adversary’s capacity to resist
– Basically a reverse blitz to counter their blitz
If you act too fast tactically you may lose a strategic opportunity
*** Beginning of Part 11 Video ***
Need to have informal loops to get information otherwise you ensure the emperor has no clothes (no information)
Once they have that information they now know what questions to ask to get that information officially
If you have an idea, you then need to test it. When you test it, you have to be prepared to be embarrassed by the results of the test. You cant just hide them and push on anyway.
Without support of people the guerrillas (or counter-guerrillas) have neither a vast hidden intel network nor an invisible security apparatus
Categories of Conflict
3 kinds of human conflict
-Attrition Warfare
-Maneuver Conflict
-Moral Conflict
Attrition:
-Firepower as a destructive force is king
-Protection is used to dilute enemy firepower
-Mobility is to bring firepower or avoid enemy fire
-MOE is body count
-Seize and hold terrain objectives
-Aim: Compel enemy to surrender and sue for peace
-High physical impact (from mental-moral-physical)
Maneuver:
-Ambiguity, deception, novelty, mobility, and violence are used to generate surprise and shock
-Firepower and movement used in combination to tie-up or divert adversary attention and strength to expose vuln/weakness
-Indications of success (instead of measures) tend to be qualitative and related to widespread onset of confusion and disorder or any other phenomenon that suggests inability to adapt to change
-Aim: Generate many non-cooperative centers of gravity, as well as disorient or disrupt those that adversary depend upon, in order to magnify friction, shatter cohesion, produce paralysis, and bring about his collapse.
Ambiguity is confusion and disorder
Deception is a false order
Can generate ambiguity faster than deception and is less risky
*** Part 12 ***
Deception campaigns take time. When you need to exploit an existing situation quickly, then you employ ambiguity.
Surprise is nothing more than a form of disorientation
Surprise and shock can also be represented as an overload beyond ones immediate ability to respond or adapt
Disorientation disrupts the ability to cope with the situation causing mental isolation
Moral:
-No fixed recipe for organization, communication, tactics, leadership, etc.
-Wide freedom for subordinates
-Heavy reliance upon moral instead of material superiority as basis for cohesion and success
-Commanders must create a bond based upon trust for cohesion
-Achieved by example. Physical energy, mental agility, and moral authority to inspire subordinates
-Benefit: Internal simplicity that permits rapid adaptability
Moral-effects are related to menace and uncertainty
Moral-strength represents mental capacity to overcome menace uncertainty and mistrust
Essence of moral conflict:
-Create, exploit, and magnify: Menace, uncertainty, and mistrust
-Idea: Surface, fear, anxiety, and alienation in order to generate many non-cooperative centers of gravity, as well as subvert those that adversary depends upon, thereby magnify internal friction
-Aim: Destroy moral bonds that permit an organic whole to exist
Looking at it positively
-Counterweights to menace, uncertainty, mistrust are Initiative, Adaptability, and Harmony
-Aim: build-up and play counterweights against negative factors to diminish internal friction, as well as surface courage, confidence, and esprit, thereby make possible the human interactions needed to create moral bonds that permit us, as an organic whole, to shape and adapt to change
Moral Values: Constraints on individual behavior so the organic whole can exist
Moral Isolation: Inability to abide by code/standards deemed acceptable or essential by those outside
When you violate those codes/standards, alienation occurs
Mental Isolation: Inability to perceive or make sense of whats going on around yourself
Pattern for Successful Operations
Goal, Plan, Action, Support, Command
Goal: Diminish adversary freedom of action while improving ours so they cant cope with events
Plan: Find strengths and weaknesses, employ variety of measures, select response that is least expected, move along least resistance, exploit friction, disorient, disrupt, overload
Action: OODA more inconspicuously, more quickly, and with more irregularity
Support: Superior comms and only essential logistics to maintain cohesion and sustain pace
Command: Decentralize in a tactical sense to encourage lower level commanders. Centralize in a strategic sense to establish aims, match ambitions with means, sketch flexible plans, allocate resources, and shape focus of overall effort
*** Part 13 ***
Intentions that make-up plan cannot happen without application of transients that make-up action
Don’t just read this, go watch the video! Here is is basically synthesizing and summarizing all the ideas he has been leading up to the whole presentation
Strategy: Penetrate adversary’s moral-mental-physical being to dissolve his moral fiber, disorient his mental images, disrupt his operations, and overload his system – as well as subvert, shatter, seize, or otherwise subdue those moral-mental-physical bastions, connections, or activities that he depends on – in order to destroy internal harmony, produce paralysis, and collapse adversary’s will to resist.
Strategic Aim: Diminish adversary’s capacity while improving our capacity to adapt as an organic whole, so that our adversary cannot cope – while we can cope – with events’efforts as they unfold
Theme for Disintegration and Collapse (see slide)
Underlying Insight: Unless one can penetrate adversary’s moral-mental-physical being … one will find it exceedingly difficult, if not impossible, to collapse adversary’s will to resist
Name-of-the-Game:
Morally-mentally-physically ISOLATE adversary from allies or any outside support as well as isolate elements of adversary or adversaries from one another and overwhelm them by being able to penetrate and splinter their moral-mental-physical being at any and all levels
How do we connect this with the national goal?
Via a sensible grand strategy that will support our national goal, pump up our resolve, drain enemies, end conflict on favorable terms, ensure that conflict and peace terms do not provide seeds for future conflict
Needed to pursue vision:
Insight, Initiative, adaptability, harmony
Wrap-Up
(i’m pretty verbose here)
Message:
He who is willing and able to take the INITIATIVE to exploit VARIETY, RAPIDITY, and HARMONY – as the basis to create as well as adapt to the more indistinct – more irregular – quicker changes of rhythm and pattern, yet shape the focus and direction of efforts – survives and dominates
or contrariwise
He who is unwilling or unable to take INITIATIVE to exploit VARIETY, RAPIDITY, and HARMONY … goes under or survives to be dominated
Game:
– Create tangles of threatening and/or non-threatening events/efforts as well as repeatedly generate mismatches between those events/efforts adversary observes or imagines (cheng/Nebenpunkte) and those he must react to (ch’i/Schwerpunkt)
as basis to
– Penetrate adversary organism to sever his moral bonds, disorient his mental images, disrupt his operations, and overload his system, as well as subvert, shatter, seize or otherwise subdue those moral-mental-physical bastions, connections, or activities that he depends upon
thereby
– Pull adversary apart, produce paralysis, and collapse his will to resist
How?
– Get inside adversary observation-orientation-decision-action (OODA) loops at all levels by being more subtle, more indistinct, more irregular, and quicker yet appear to be otherwise
Implications:
– In a tactical sense, these multi-dimensional interactions suggest a spontaneous, synthetic/creative, and flowing action/counteraction operation rather than a step-by-step, analytical/logical and discrete move/countermove game
(complexity – variety without harmony)
– In a strategic sense, these interactions suggest we need a variety of possibilities as well as the rapidity to implement shift among them
– Why?
– – Ability to simultaneously and sequentially generate many different possibilities as well as rapidly implement and shift among them permits one to rapidly generate mismatches between events/efforts adversary observes or imagines and those he must respond to
Variety/Rapidity allows one to:
– Magnify adversary friction hence stretch out his time to respond in a directed way
Harmony/Initiative permit one to:
– Diminish own friction hence compress own time to exploit variety/rapidity in a directed way
Altogether they enable one to:
– Operate inside adversary’s OODA loop to enmesh adversary in a world of uncertainty, doubt, mistrust, confusion, disorder, fear … and/or fold adversary back inside themselves so they cannot cope with events/efforts as they unfold
Simultaneously – by repeatedly rolling thru OODA loops while appealing to and making use of the ideas in grand strategy and theme for vitality and growth we can:
– Evolve and exploit Insight/Initiative/Adaptability/Harmony as a basis to:
– – Shape or influence events so that we not only amplify our spirit and strength (while isolating theirs) but also influence the uncommitted or potential adversaries so they are drawn toward our philosophy and are empathetic toward our success
The Art of Success:
– Appear to be unsolvable cryptogram while operating in a directed way to penetrate adversary vulnerabilities and weakness in order to isolate them from their allies, pull them apart, and collapse their will to resist
Yet
– Shape or influence events so that we not only magnify our spirit and strength but also influence potential adversaries as well as the uncommitted so they are drawn toward our philosophy and are empathetic toward our success
Epilogue
Central Theme:
Evolve and exploit insight/initiative/adaptability/harmony together with a unifying vision, via a grand ideal or an overarching theme or a noble philosophy, as basis to:
– Shape or influence events so that we not only amplify our spirit and strength but also influence the uncommitted or potential adversaries so that they are drawn toward our philosophy and are empathetic toward our success
yet be able to
– Operate inside adversary’s OODA loops or get inside his mind-time-space as basis to:
– Penetrate adversary’s moral-mental-physical being in order to isolate him from his allies, pull him apart, and collapse his will to resist
END OF BRIEF
*** Part 14 ***
Questions
Boyd interestingly comments on Russian disinformation here.
He says we also pump out disinformation and you should have deception but it better work and you better know what you are doing. Becomes harder over time as real information comes out.
If its not going right, you have to face up to it and correct. Can be one of the hardest things.
Links
https://www.airuniversity.af.edu/Portals/10/AUPress/Books/B_0151_Boyd_Discourse_Winning_Losing.PDF
