The battle of Moncontour (3 October 1569) was a major Catholic victory during the Third War of Religion that followed the unsuccessful Huguenot siege of Poitiers, and seemed to bring the Protestant cause to its knees. After recovering from an earlier defeat at Jarnac, the Huguenots received reinforcements from Germany, and against the advice of Admiral Coligny, the senior Huguenot commander, decided to besiege Poitiers (27 July-7 September 1569). The siege dragged on for so long partly because the Royal army had been disbanded after the spring campaign, but by early September Henry, duke of Anjou, the future Henry III, was ready to move (Anjou was officially in charge, but the real command was probably held by Gaspard de Tavannes).
Anjou did not believe that he was strong enough to risk a direct attack on Coligny's army around Poitiers, so instead he moved to attack Châtellerault, a Huguenot-held city 18 miles to the north. A breach had soon been battered in the walls, forcing Coligny to lift the siege of Poitiers. On 7 September he marched north. Anjou moved north-west to Chinon, further down the river Vienne. Coligny followed him for a short distance, then crossed to the left bank of the Vienne and took up a position at Faye-la-Vineuse, fifteen miles to the south of Chinon. Coligny's plan was to move into southern Poitou, where he could link up with the Army of the Viscounts, a successful Huguenot army that had recently re-conquered Bearn.
Anjou moved before Coligny. On 29 September the Royal army crossed the Vienne, and reached Loudun, due west of Faye. On 30 September Coligny began by moving south, then swung to the west to head towards Moncontour, on the River Dive. This meant that he was advancing across the route being taken by the Royal army, and the Huguenot rearguard ran into trouble at Saint-Clair, four miles to the east of the river. Coligny was able to extract his army from a dangerous situation, and by the end of the day had reached comparative safety at Moncontour, where he was protected by the line of the fast-flowing Dive.
Coligny was now faced by a crisis within his army. Although the Huguenots were probably outnumbered, and had not yet recovered from the siege of Poitiers, most men in the army wanted to fight. Coligny was less eager, and would have preferred to unite with the Army of the Viscounts first, and so he had to disguise his plans.
On the night of 2-3 October the Huguenot army was ordered to prepare to march south-west to Airvault, where it could cross the River Thouet. At the same time the Royal army was on the move, heading south to get around the upper reaches of the Dive. On the morning of 3 October Anjou was moving north, towards Moncontour.
If Coligny had been able to move when he had wanted, Anjou's bold move would have failed, but on the crucial morning the Huguenot's German troops mutinied and demanded to be paid. It took two hours for order to be restored, by which time Anjou had appeared from the south and it was clear that a battle would have to be fought.
Anjou's first move was to try and deploy to the west to block the Huguenot line of retreat towards Airvault, but Coligny prevented this by ordering Louis of Nassau to block him with the 'battle', in this case the right wing of the army. Nassau's line stretched out to Douron, about half way between the two rivers. Coligny commanded the Huguenot 'van', which was deployed on the left, to the north-east of Nassau.
The Catholic line was deployed with its van (under the Duke of Montpensier) on the right, facing Coligny, and the 'battle', under Anjou, was on the left. The Catholics also had a reserve, under Biron.
The exact size of the two armies is uncertain, although most sources agree that the Huguenots were outnumbered. Coligny had 6,000 cavalry and 12,000-14000 infantry, while Anjou had 7,000-8,000 cavalry and 16,000-18,000 infantry. The Huguenots had a strong German contingent, the Catholics a Swiss contingent.
The battle began with a clash between the two vans (the Protestant left and Catholic right). The Huguenot left was put under severe pressure, and Coligny was forced to call for aid from the right. He then led a charge against the German reiters, who were advancing with John Philip I, Rhinegrave of Salm-Dhaun Rhinegrave at their head. Coligny almost certainly killed the Rhinegrave himself, before being wounded and forced to retire to the rear for treatment.
On the Royal side Anjou led his own cavalry in an attack that left him dangerously exposed. The reserve was ordered into the fray to restore the line, and their extra pressure began to force the Huguenots back. The Huguenot's reiters made a disastrous attack on the Swiss, and then fled from the field. This left the landsknechts exposed to attack by the Swiss, who massacred them, killing around 3,800 out of a total of 4,000. This represented nearly half of the Huguenot casualties of 8,000.
After a battle that lasted for four hours the Huguenots were forced to retreat. Louis of Nassau and Wolrad of Mansfeld were largely responsible for the escape of the surviving part of the army (10,000-12,000 men depending on the actual size of the army). The retreating Huguenots were able to cross the Thouet at Airvault, and then moved to Partenay and finally to safety at Noirt.
The Catholics failed to take advantage of the crushing nature of their victory. Instead of pursuing the defeated Huguenots, Anjou decided to concentrate on capturing their cities. On 10 October he began a siege of Saint-Jean d'Angély that would last until 3 December and prove to be just as fatal to the Royal cause as the siege of Poitiers had been for the Huguenots. This gave Coligny the time he needed to raise a new army in the south of France, which he then led back into the north in 1570, eventually forcing the court to come to terms at St.-Germain on 8 August 1570.