The siege of Rouen (11 November 1591-20 April 1592) was an unsuccessful attempt by Henry IV to gain control of Normandy and the Seine below Paris (Ninth War of Religion).
Henry spent much of 1591 attempted to gain support from the Protestant powers of Europe. Turenne had raised 14,000 men in Germany. Elizabeth I had also offered support, originally demanding that she should be allowed to occupy Calais. Henry refused to accept these terms, but eventually agreed to attack Rouen instead. Elizabeth then sent 6,000 men under the earl of Essex. Henry also had 6,000 Swiss troops and 4,000 French infantry, giving him 30,000 men, one of his larger armies.
The capture of Rouen would have given Henry control of most of Normandy, then the richest part of northern France, and would also have given him control of the Seine from Paris to the sea.
Rouen was defended by at least 6,000 men, commanded by André de Villars-Brancas (although he was officially the second in command for Duke Henry d’Aiguillon, the son of the duke of Mayenne). Villars moved guns into the city from Le Havre and reinforced the garrison.
Marshal Biron was given command of the first part of the siege. The siege began on 11 November 1591, and Biron concentrated his efforts against Fort Saint Catharine. This was a strong position, and held out against repeated attacks. Biron was soon joined by Essex, and by Henry IV on 23 November. At the start of December Henry sent a conciliatory message to the defenders in an attempt to convince them to surrender, but this was rejected. Essex didn’t stay for long, and returned to England in January 1592.
The morale of the defenders and citizens was high, bolstered by their determination not to accept a heretic as king. It was reinforced by an impressive religious service and procession on Sunday 8 December, led by the Bishop of Bayeux and featuring every relic in the city. The defenders were also in touch with the Spanish, who were able to get into the city up the Seine.
The best hope for the garrison was that they would be relieved by the Spanish, who had a strong army in the Low Countries, led by the very able Alexander Farnese, prince of Parma. The Spanish agreed to come to the aid of Rouen in return for being allowed to place a garrison in La Fère, on the Oise near the Flemish border. Parma joined with Mayenne and Guise on 28 December 1591, and by mid-January had 13,546 infantry and 4,061 cavalry. He then began a careful advance towards Rouen.
Henry was less careful. He led a force of cavalry and a few infantry east to try and harass the Spanish, but in the first clash with them, near Aumale on the Bresle, close to the border between Normandy and Picardy, Henry was wounded. He was unable to stop the Spanish advance, and Parma soon reached Neufchatel in Bray. On 26 February, while Henry was away from the siege Villars launched a sortie from Rouen, capturing many of Biron’s cannon and wounding the Marshal himself.
Parma now had a clear route to Rouen, but Mayenne didn’t want the Spanish to actually take possession of the city. Villars also appears to have been worried about the same thing, and sent a message to Parma announcing that Rouen could now take care of itself. Under pressure from both of his French allies, Parma withdrew to Picardy where he besieged Rue (near the coast just to the north of the mouth of the Somme).
Villars soon regretted his actions. Henry returned to take direct control of the siege, and Rouen was soon under more pressure than before. Villars was forced to send a message to Parma pleading for help, and announcing that Rouen would have to surrender on 20 April if none came. Parma reacted quickly, and reached the vicinity of Rouen in only six days.
This nearly caused a crisis for Henry, who had believed that Parma would need twenty days to reach Rouen from Picardy, and had allowed many of his nobles to take a break, leaving the infantry to conduct the siege. Henry was forced to abandon the siege, and on 21 April Parma and Mayenne entered the city in triumph.
After raising the siege, Parma and Mayenne moved north to besiege Caudebec, half way between Rouen and the sea. During this siege Parma was wounded, and it also gave Henry time to gather his armies once again. Parma and Mayenne found themselves trapped in the area between the Seine and the coast, and were soon pinned against the river, but just as Henry was planning to attack their camp, Parma erected a pontoon bridge across the river and slipped away. He then moved east to Paris, before returning to the Spanish Netherlands, where he died on 2 December 1592.