Ambush An ambush is a long - established military tactic , in which the aggressors ( the ambushing force ) take advantage of concealment and the element of surprise to attack unsuspecting enemy combatants from concealed positions , such as among dense underbrush or behind hilltops . Ambushes have been used consistently throughout history , from ancient to modern warfare . History . In ancient times , an ambush often might involve thousands of soldiers on a large scale , such as over a mountain pass . Ambushes appear many times in military history . One outstanding example from ancient times is the Battle of the Trebia river . Hannibal encamped within striking distance of the Romans with the Trebia River between them , and placed a strong force of cavalry and infantry in concealment , near the battle zone . He had noticed , says Polybius , a " “ place between the two camps , flat indeed and treeless , but well adapted for an ambuscade , as it was traversed by a water - course with steep banks , densely overgrown with brambles and other thorny plants , and here he proposed to lay a stratagem to surprise the enemy ” " . When the Roman infantry became entangled in combat with his army , the hidden ambush force attacked the legionnaires in the rear . The result was slaughter and defeat for the Romans . Nevertheless the battle also displays the effects of good tactical discipline on the part of the ambushed force . Although most of the legions were lost , about 10 , 000 Romans cut their way through to safety , maintaining unit cohesion . This ability to maintain discipline and break out or maneuver away from a killing zone is a hallmark of good troops and training in any ambush situation . See Ranger reference below . Another famous ambush was that sprung by Germanic warchief Arminius against the Romans at Battle of the Teutoburg Forest . This particular ambush was to have an impact on the course of Western history . The Germanic forces demonstrated several principles needed for a successful ambush . They took cover in difficult forested terrain , allowing the warriors time and space to mass without detection . They had the element of surprise , and this was also aided by the defection of Arminius from Roman ranks prior to the battle . They sprung the attack when the Romans were most vulnerable - when they had left their fortified camp , and were on the march in a pounding rainstorm . They did not dawdle at the hour of decision but attacked quickly , using a massive series of short , rapid , vicious charges against the length of the whole Roman line , with charging units sometimes withdrawing to the forest to regroup while others took their place . The Germans also made use of blocking obstacles , erecting a trench and earthen wall to hinder Roman movement along the route of the killing zone . The result was mass slaughter of the Romans , and the destruction of 3 legions . The Germanic victory caused a limit on Roman expansion in the West . Ultimately , it established the Rhine as the boundary of the Roman Empire for the next four hundred years , until the decline of the Roman influence in the West . The Roman Empire made no further concerted attempts to conquer Germania beyond the Rhine . Procedure . In modern warfare , an ambush is most often employed by ground troops up to platoon size against enemy targets , which may be other ground troops , or possibly vehicles . However , in some situations , especially when deep behind enemy lines , the actual attack will be carried out by a platoon , a company - sized unit will be deployed to support the attack group , setting up and maintaining a forward patrol harbour from which the attacking force will deploy , and to which they will retire after the attack . Planning . Ambushes are complex , multi - phase operations , and are , therefore , usually planned in some detail . First , a suitable killing zone is identified . This is the place where the ambush will be laid . It ' s generally a place where enemy units are expected to pass , and which gives reasonable cover for the deployment , execution , and extraction phases of the ambush patrol . A path along a wooded valley floor would be a typical example . Ambush can be described geometrically as : Preparation . To be successful , an ambush patrol must deploy into the area covertly , ideally under the cover of darkness . The patrol will establish secure and covert positions overlooking the killing zone . Usually , two or more “ cut - off ” groups will be sent out a short distance from the main ambushing group , into similarly covert positions . Their job is twofold ; first , to give the ambush commander early warning of the approaching enemy , and second , when the ambush is initiated , to prevent any enemies from escaping . Another group will cover the front and rear of the ambush position ( blocking force ) , and thus provide all round defence . Care must be taken by the ambush commander to ensure that fire from any weapon cannot inadvertently hit any other friendly unit ( this is known as crossfire ) . Waiting . Having set up the ambush , the next phase is to wait . This could be for a few hours , or a few days , depending on the tactical and supply situation . It is obviously much harder for an ambush patrol to remain covert and alert if sentry rosters , shelter , sleeping , sanitary arrangements , food and water , have to be considered ; so this should be done in a patrol harbour , away from the site chosen for the ambush . Ambush patrols will almost always have to be self - sufficient , as re - supply would not be possible without compromising their position . Execution . The arrival of an enemy in the area should be signalled by one of the cut - off units . This may be done by radio or by some other signal , but the enemy must not detect the signal . If radio silence is necessary , the pre - electronic expedient of a cord linking the groups , tugged once or twice as a signal , may be employed . The ambush commander will have given a clear instruction for initiating the ambush . An ambush is ideally initiated by the most effective casualty - producing device available to the attacking elements . This might be a burst from an automatic weapon , or the use of an antipersonnel explosive device ( such as a Claymore mine or other directional weapon ) . Some military doctrines call for an ambush to be initiated by a signal from a whistle , though in US practice , whistles are not favored , since they do nothing to inflict damage on the enemy . The ambush commander may judge when the ambush will be most effective , and give the signal manually , or the ambush patrol may rely on tripwire or pressure - detonated mines in the kill zone to initiate firing . Against vehicles , the lead and rear vehicles are the primary targets ; this traps the remaining vehicles in the kill zone for as long as possible . Targets are prioritised to rapidly destroy the target ' s unit cohesion . It is vital to obtain fire superiority as rapidly as possible , to prevent enemy counter - ambush tactics from being executed . The order of priorities against an enemy infantry unit is the enemy radio operator ( in the past identified by the whip aerial of the backpack radio unit such as the British Army ' s Clansman system ) , the enemy ' s unit commander ( a more difficult task today when officers and NCOs are dressed and armed in an identical manner to the rest of the infantry squad ) , and the platoon or section machine - gunner . After the firefight has been won , the now compromised ambush patrol must leave the area as soon as it is practical to do so . In hit - and - run operations , especially against superior numbers and forces , the ambush force will begin disengaging even before the firefight has been won . In the past , accepted protocol was to check bodies for intelligence , take prisoners , and ' treat ' any wounded enemy . Once this was accomplished , the ambush patrol would then exfiltrate the area by a pre - determined route . If time has allowed for it , the ambush force will have prepared their exit ; for example , placing land mine s to cover their retreat , with the members of the force making , and following , a safe route through the mines . If possible , a subsidiary ambush may be planned along the exit route to catch pursuing troops , and , if available , the egress may be covered by mortar or artillery fire . Surviving . By definition , the ambush contains the element of total surprise ; which means the victims of the ambush have no knowledge of how it has been constructed , or of what measures may have been employed to prevent escape . Therefore – and this has been proven by the experience of war – the only " likely " method of survival is withdrawal from the killing zone " the way you came in " . All other routes out of the killing zone may be blocked , and in a very well - planned and well - executed ambush , even the " back door " will have been closed by the time the ambush is sprung , though perhaps not as securely . The published military doctrine is " immediate , positive , and offensive action " against the ambush . But this is very likely to have been anticipated by the ones who set the ambush , and often plays into their hands . The value of withdrawal is the preservation of the force to " live to fight another day " , when not taken by surprise . Avoiding . The best way to survive an ambush is not to encounter them . In order for this to happen , patrol movement mustn ' t be predictable in timing or route , and should avoid the most obvious routes . Rather than moving at a constant speed and direction , the patrol should vary these , with occasional stops to observe both the route ahead , and changes behind . Units should move in such a way that they are close enough together for mutual support , but far enough apart so that one burst of automatic fire wouldn ' t take out the entire unit . When on foot , if possible , the patrol should move in such a way as to maximise their firepower ; for example , with the arrowhead and spearhead formation , they should not allow themselves to be skylined . Units on foot should have a point man some way ahead of the main body , and , if possible , a rearguard as well . Those travelling in vehicles follow the same procedures , with lead and trailing vehicles well ahead of , and well behind , the main body of vehicles . Countering . In the modern day warfare , this is much easier than before , since a route can be " sanitized " with saturation suppressive fire beforehand by aerial assets ( e . g . , with rotating barrel miniguns ) , and any obvious ambush sites noted , and counter measures taken . During the Soviet war in Afghanistan , Mi - 24 Hind gunships were used to locate concentrations of mujahideen guerrilla , and these would then be attacked by the Hinds themselves , or by artillery , using the aircraft as spotters .