The battle of Arques (21 September 1589) was a victory for Henry IV early in the Ninth French War of Religion, and saw him defeat the duke of Mayenne, the new leader of the Catholic League.
The Eighth War of Religion, or War of the three Henrys, had seen a series of dramatic changes in the balance of power. At one point Henry of Navarre had faced an alliance of the Catholic League of Henry of Guise and Henry III, but the king then had Guise and his brother murdered, forever destroying any chance he had of winning over the League. Henry’s only option was to turn to Henry of Navarre, and the two men agreed an alliance and besieged Paris. Early in the siege Henry III was assassinated by a fanatical monk from Paris. Henry III acknowledged Henry of Navarre as his heir before he died. This marked a chance in the nature of the war, marking the point where the Eighth War turned into the Ninth.
The new Henry IV managed to gain the acknowledgement of Henry III’s former supporters, but a significant number refused to fight under him, and Henry IV was unable to continue with the siege. He lifted the siege, split his army up, and led a large part of it north into Normandy. His aim was to try and secure control of that wealthy province, as well as meet up with reinforcements he was expected from England.
In the aftermath of the death of Henry of Guise, control of the Catholic League passed to Guise’s brother, Charles duke of Mayenne. He decided to follow Henry into Normandy and either defeat and capture him or force him to flee into exile.
Henry IV was badly outnumbered. He appears to have had around 1,200 cavalry, 3,000 French infantry and two regiments of Swiss infantry (perhaps another 1,000 men). Mayenne is given between 3,000-4,000 cavalry and 15,000-20,000 infantry.
The battle took place in a river valley to the south-east of Dieppe. Three rivers - the Varenne, Bethune and Eaulne merge to form the Arques River (the Bethune and the Varenne merge in the area around the village, the Eaulne flows in to the north). The combined river then flows into the sea to the east of Dieppe. Mayenne was approaching from the east, so needed to cross the Eaulne and then the Bethune to reach a road that ran along the west bank of the Arques into Dieppe.
Henry had plenty of warning that Mayenne was on his way, and decided to defend the river crossing at Arques. He built a fortified camp near the village, where his position was supported by the guns of the castle of Arques, which overlooked the valley. This position was defended by an outer ditch and inner earthworks and cannon.
Mayenne attacked the camp on 21 September, under the cover of a thich fog.. His plan was to send a party of German mercenaries forward to pretend to desert. If this ploy worked, then they would be supported by two French regiments. This attack took place around the Maladrerie, part of Henry’s lines that ran near a leper hospital (possibly on his right, to the south of Arques). The Swiss defenders of that part of Henry’s line fell for the ploy, and the Maladrerie was taken by Mayenne’s men.
Henry joined the Swiss, and with the support of reinforcements led by Chatillon, attempted to restore the situation. He was aided by a change in the weather - the fog cleared, allowing the guns in the castle to fire on Mayenne’s advancing forces. Biron and Coligny recaptured the Maladrerie, and Mayenne’s attack ended in failure.
In the aftermath of this victory Henry began to receive reinforcements, including 4,000 men sent by Elizabeth I of England. This allowed him to go onto the offensive, and attempt a second siege of Paris, but this ended in failure after Mayenne arrived to defend the city.