The battle of Ivry (14 March 1590) was Henry IV’s second battlefield victory over the forces of the Catholic League, and allowed Henry to launch his second and longest siege of Paris (Ninth War of Religion).
In the summer of 1589 Henry of Navarre had been engaged in a siege of Paris alongside Henry III, but early in the siege the king was assassinated. Henry of Navarre came to the throne as Henry IV, but he was unable to win over many of Henry III’s Catholic allies, and the army besieging Paris fell apart. Henry IV lifted the siege and led part of his army into Normandy, where he defeated the new leader of the Catholic League, Charles of Mayenne, at the battle of Arques (21 September 1589). In the aftermath of this victory Henry’s army grew to be nearly 20,000 strong, and his risked a second siege of Paris (November 1589). Although his troops sacked the left bank suburbs, they were unable to break into the city, and after Mayenne arrived to support the defenders, Henry abandoned the siege and moved south, where he took over Henry III’s administration at Tours.
The war resumed in the spring of 1590. Mayenne besieged Meulan, downstream from Paris. Henry moved to besiege Dreux, west of Paris and south of Meulan. This move threatened Paris, and Mayenne was forced to move south to try and lift the siege.
Once again Mayenne had the larger army. He had a total of 16,000 men under his command - 12,000 infantry and 4,000 cavalry, including a contingent provided by Philip II of Spain and commanded by Philip, count of Egmont. This may have been as large as 6,000 infantry and 1,200 cavalry, in which case it made up half of Mayenne’s army. Henry had 11,000 men - 8,000 infantry and 3,000 cavalry. The two cavalry forces fought in very different ways. Egmont’s men were lancers, excellent shock troops. Henry’s men used the pistol and sword, and were more mobile and more effective in the melee.
The two armies met at Ivry, a few miles to the north of Dreux. Both sides had time to deploy their troops carefully. Henry mixed his infantry and cavalry all the way along his line, with seven cavalry squadrons, most of which were supported on both flanks by infantry. From left to right the cavalry was commanded by Marshal Jean d’Aumont, Francois de Bourbon duke of Montpensier, Baron Biron (son of the Marshal), Count Givry and the Count of Auvergne, Henry IV, Marshal Armand Biron and Count Schomberg. Marshal Biron’s squadron was withdrawn behind the main line to serve as a reserve. His son and Givry and Auvergne’s squadrons were placed slightly ahead of the rest of the line, with Henry’s main artillery battery between them.
On the Catholic side the Duke of Nemours commanded on the right, the Chevalier d’Aumale on the left and the Duke of Mayenne in the centre, also with infantry spread between the cavalry, but with less space between the different units.
The battle began with a brief artillery bombardment of the League lines, before the Catholic cavalry began a series of attacks on the French lines. This was then followed by a clash between the main body of the League cavalry and Henry’s own squadron, in which the king got somewhat ahead of most of his men, and for some time was in real danger. Before the battle started Henry urged his men to follow the white plume on his hat if they couldn’t see his standards, as ‘that way lay victory and honour’. This did indeed help keep his men together, and despite being outnumbered they had the best of this battle, and within an hour the bulk of the League cavalry had been defeated and was fleeing from the field. Henry was then able to commit Biron’s reserves to the pursuit, and Mayenne and his men were chased back to Mantes and the Seine. The infantry never really got involved in the fight.
In the aftermath of the battle Henry attempted to spare any French troops who fell into his hands. He also accepted the surrender of the Swiss troops in Mayenne’s army (after they threatened to fight to the death if they didn’t get good surrender terms), but the German mercenaries were slaughtered. The official Royal report claimed that the League had lost 1,500 cavalry dead and 400 prisoners, and their overall losses may have been as high as 4,000. Amongst the dead was Egmont. Henry lost around 500 men.
In the immediate aftermath of the battle Henry had a really good chance to win the war in one move, by heading east to nearby Paris, which was undefended and in a state of panic. Instead he decided to spend almost two weeks at Mantes, before making a slow progress towards Paris. By the time he got there, the Parisians had recovered their nerve, and Henry’s second siege of Paris (7 May-30 August 1590) ended in failure.