The period stretching from the end of the seventeenth century to first half of the eighteenth century is often considered as a period of “limited warfare”. Battles were rare, and when they happened, they were largely described and analysed, on both sides, by soldiers and civilians. Yet, describing a battle is not an easy task for an historian. Available accounts are often contradictory. No one can claim to give a detailed description of the behaviour of each regiment. At worst, they can be misleading, to hide or to insist on the responsibility of a decision-maker. Finally, contemporary texts generally give only factual descriptions (tactical handling of the troops, number of losses…) and neglect the human side of the battle: what soldiers experienced during this day. However, these difficulties should not lead historians to avoid such a work. But they should make them more aware of the necessity to discover and exploit a wide range of different sources. This article takes the battle of Oudenarde as an example to introduce the different documents an historian may use to analyse an early modern battle, from military correspondence to gazettes and courtiers memoirs. To narrow the scope of the study, this paper is restricted to French and contemporary documents, and does not examine graphical and literary representations of the battle. The example of the struggle of Oudenarde was chosen because this event appeared, even for contemporary writers, very hard to describe. Armies were huge comparing to eighteenth-century standards: nearly 100 000 men on both sides (but a large part of them did actually not fight). Moreover, the ground was uneven, and divided by rows of defiles. At last, no precise order of battle was observed, soldiers being sent to the enemy as soon as they arrived on the battlefield. The major sources to describe such an event are letters and accounts coming from eyewitnesses. All letters sent by French generals and officers to Louis XIV, or to his secretary of war Michel Chamillart, are still available at the Army historical Service. Within these archives, one of the most important pieces is the letter, written by the commander in chief, announcing a battle and its outcomes. In this letter, the general is supposed to be able to give a comprehensive account of the day, to assess the losses on both sides, and to explain what the army is just about to do. Unfortunately, this is not always true, as it is shown by the example of the letter written by duke of Vendôme the very next day after the battle. Vendome refuses to give a detailed description of the operations, insisting rather on the attitude of Bourgogne’s entourage. Indeed, the letter of Vendôme is less intended to relate the battle than to defend his own action. The tactical handling of the battle, which is not a credit to him, is neglected. On the contrary, Vendôme put an emphasis on the brave behaviour of some regiments, which he has personally led. So the account produced by the commander in chief is not sufficient to have a reliable description of the battle. Louis XIV and Chamillart were fully aware of this problem: that is the reason why, after every struggle, they asked for general officers to give their own narratives of the day. Officer letters give to historians two kind of information. At first, they help documenting “decision-making” processes during a battle. For example, narratives of high-level officers are very useful to analyse when and how the two major choices of the battle of Oudenarde were taken: deciding to engage the French army and deciding to retreat. Thanks to the account of marshal of Matignon, we can estimate that Vendôme resolved committing troops to battle at twelve (that is sooner that Saint-Simon said in his memoirs, but latter than Vendôme claimed in his missives to the king). Thanks to the account of earl of d’Artagnan, we discover that before asking to Vendôme, most important French general officers gathered and came for retreat. The war council held by Vendôme and Bourgogne only acknowledged their will. The second kind of information given by officer accounts is related to the way of fighting at the beginning of the eighteenth century. Every general officer was supposed to lead troops personally. They had to describe to Versailles how their own soldiers fought. This brings a lot of very lively information on contemporary warfare, for infantry and cavalry as well as for artillery. We may also find, in military correspondence, missives from lesser-ranked officers, such as brigadiers. However precious these sources may be, historians should be cautious with them. When writers sent their letters to the secretary of war, they commonly hoped a reward in return, for them or for their units. Therefore they exaggerate frequently the value of actions they described. On the other hand, they did not want to criticise too harshly their superiors or their fellow generals, to avoid leading their targets to become their enemies. That is the reason why personal letters sent to parents or friends are of major interest. They are unfortunately harder to find, but some of them were sometimes discovered within military or diplomatic archives. At last, historians can discover and exploit within official archives a various range of figures, from regimental loss assessments to evaluations of global logistic needs. To know how the defeats were viewed from Versailles, we can use memoirs written by courtiers. Their day-to-day description of every event shows us how civilians progressively became aware of the seriousness of these reverses. At first, they heard only rumours and contradictory news. Vendôme’s description of the battle reassured them, and Bourgogne’s letter frightened them. After having expected reliable information several days, and even several weeks, they became conscious that Audenarde was actually a defeat. On the opposite, French gazettes constantly kept claiming that Louis XIV’s armies had not been really beaten. These newspapers (often directly written by government officials) engaged an information struggle against allied gazettes on the assessment of losses on both sides. The number of dead and wounded was in fact a major criterion to decide if Audenarde was a French defeat, or not. At least, we may assess the usefulness of French sources for historians. Very few of these sources give a panoramic view of the battle. French officers having been able to have a look at the whole battlefield, as Bourgogne, did not write on the battle. Both French officers and gazettes preferred insisting on few courageous actions performed by some regiments, rather than painting a more detailed – but less honourable – picture of the battle. Actually, French sources never speak of the battle, but of the struggle of Audenarde. Yet, whatever their bias may be, these sources have to be taken into account. First, some of them are very interesting to give a view of the battle at the lower level, the one of the soldier. Second, they allow historians to have several angles on such an event: for example, the Natzmer attack, considered on allied side as a turning point of the battle, is sincerely seen by French sources as a success for Louis XIV’s cavalry. Third, they are a good way not to forget that in most cases, the problem of determining who was victorious after a battle was not a simple one. Audenarde would really not have been an allied victory, if Marlborough and Prince Eugen have thought themselves unable to perform the siege of Lille, and have decided to retrieve. The fate of a battle is frequently decided a long time after the end of the fight.