It is not easy to start from a consensus to define tactical surprise, as the concepts they cover are so numerous. Outside the national framework, it can already be noted that surprise is defined as a principle of war in the doctrine of NATO or countries such as China, the United States, the United Kingdom, Israel and Russia. In the French doctrinal corpus, surprise is understood as a process for applying the principles of war. As head of the military history, strategy and general tactics course at the École supérieure de guerre, Foch set out a series of principles as early as 1893, without, however, aiming to be exhaustive: economy of forces, freedom of action, free disposition of forces, safety, etc.

The surprise appeared here in its negative sense, mirroring the safety that allowed to protect against it. The three principles of war in their present form, namely freedom of action, concentration of effort and economy of means, were retained in the general instruction.The three principles of warfare in their current form, namely freedom of action, concentration of effort and economy of means, were retained in the 1994 general training of land forces, and then repeated in 2008 in the FT-02 document, where it is however specified that "their application procedures must give priority to surprise in all areas because it makes it possible to impose a permanent delay on the adversary". It is interesting to note that, in the early 1990s, Admiral Labouérie already called for a clear distinction to be made between the principles of warfare and the generic process of surprise. But can surprise not be considered as an effect on theenemy?Surprise certainly refers to an unforeseen action by the enemy, from which he has, at best, only very imperfectly protected himself. But it is also the emotional state caused by the discrepancy between reality and our expectations, which can go as far as stunned ration and paralysis. Ultimately, tactical surprise, whether offensive or defensive, can be defined as much by an action in the military domain as by the result of that action, which requires the victim to adjust his posture and means within a limited space-time frame.

Regardless of the meaning chosen, surprise remains aconstant factor inarmed conflicts despite its use, often sporadic over the centuries. Indeed, it is intrinsically linked to war because it exploits the uncertainty and fog inherent in any dialectic of wills. This observation raises the question of whether it is possible to surprise or be surprised, at a time when the battlefield is transparent. Can the argument of the total knowledge of the terrain and environment that current technology would confer justify the impossibility of tactical surprise today? Secondly, technology does not eliminate the capacity for surprise, since it brings as many opportunities as vulnerabilities for the leader who has always wanted to be omniscient on the battlefield. Finally, the access to technologies favouring surprise (drones, guided rockets, ...) for non-state groups on the one hand and the current dependence of Western countries on digital systems on the other hand, raise the question of the appearance of new vectors of surprise. In short, surprise still seems possible today.

Surprise is one of theconditions forvictory inthe context of an unfavourable or equal balance of power. Indeed, it allows the search for military superiority and psychological ascendancy over an adversary in a well-defined space-time framework, a condition eminently favourable to tactical success. Its implementation must therefore be an integral part of the military leader's thinking when designing his manoeuvre, in the same way as its safety. Indeed, the notion of surprise being obviously developed in the face of an enemy, the latter will certainly seek it for his own benefit. Safetyis thus fundamentally inseparable from surprise. Moreover, NICTs offer a new dimension to the notion of safety, notably because of the hyper-connectivity, the networking of numerous systems and the infovalorisation allowed by the SCORPION programme.

In order to include surprise in his manoeuvre, the leader must first and foremost master the mechanism and conditions for success. First of all, surprise directly exploits theuncertainty on the battlefield. This uncertainty is largely linked to the environment (meteorology, social and political contingencies, ...) and to the impregnability of the battlefield. visibility ofhuman nature,which make it extremely difficult, if not impossible, to characterize all the actions and reactions of the enemy. Secondly, the greater thedistortionbetween what was expected and reality, the greater the surprise effect and the longer its duration will be.¹. This gap will be all the greater as the manoeuvre will be furtive until thedecisive moment and will call upon a trick or an innovative stratagem, the fruit of the chef's inventiveness. This will necessarily be based on the vulnerabilities of the adversary determined by intelligence obtained with adapted technologicalcapacities . But surprising an adversary, like any other military action, requires doctrine, training and education to be effective. The development of a culture ofsurprise, permeating down to the lowest echelons, appears here to be imperative. Moreover, surprise is only worthwhile if it preserves its unpredictability and the enemy's doubts, underpinned by operationalsecurity and respect for secrecy . Finally, surprise is only useful if it is followed by anoperational phaseexecuted at the decisive moment and ordered by a leader capable of quickly grasping the whole situation on the battlefield.

It is now up to the leader to define the factors for theapplication of surprise that will makeit resonate with his manoeuvre. There are four of them:the time, the place, the mode of action and the technological vehicle.². Their combination is intended to cause or exploit vulnerabilities in the enemy's security posture. In terms of timing, if discretion is sought, night-time movement is preferred. If, on the contrary, we seek to disappoint by focusing the enemy's attention on one of our movements to mask another, we will give priority to a daytime manoeuvre. Determining the place of surprise is a physical point on the ground where the enemy is not expecting us, either because he has not considered it, or because he has judged it too difficult to access or unsuitable for use in combat. In terms of mode of action, changing the pace of the maneuver, infiltrating the depths or searching for the archipelagic com- bat are examples used to surprise and destabilize the opponent. Finally, a surprise will have all the more effect on the enemy if it is carried by an innovative capacity resulting from a jump or a technological breakthrough (precision, range, power, protection, stealth, ...). To conclude on the points of application of surprise in manoeuvres, it is interesting to note that certain operational superiority factors3, whether or not combined with other key factors, appear as effect multipliers for the purposes of surprise or safety. Surprise can thus be analysed through the prism of mass, the combination of agility with command performance or influence.

At the same time, the leader must also think about safety. This will be based upstream on the knowledge/anticipation function. The aim here is to "think the unthinkable future" thanks to intelligence and foresight, and then to put in place appropriate security measures. In this context, the identification of weak signals, the setting up of scenarios describing the threat, or comparative analysis techniques such as net assessment, etc., will be used.⁴ are commonly used leads today. Always upstream, training and resilience training of soldiers,infrastructures and combat systems help reduce the effect of surprise. Working in degraded mode (CIS shutdown, loss of key units or capabilities, etc.) must be imposed and facilitated by the implementation of business continuity or recovery plans. With regard to the conduct of operations,short-loop intelligence, the modularity and adaptability of units are security factors which would not be complete without mentioning the establishment of a reserve contributing to the freedom of (re)action of the leader.

1 Theoretical Tactics, General Yakovleff, ECONOMICA, 2016.

2 The future of tactical surprise in the age of innovation, Rémy Hemez, IFRI, 2016.

3 Future Land Action, EMAT, 2016.

4 Comparative analysis of the military, technological, political, economic and other factors that determine the relative military capability of nations. Its objective is to identify problems and opportunities that deserve the attention of defence policymakers.