The battle of Dormans (10 October 1575) was the only significant battle during the Fifth War of Religion (1575-76) and saw a Royal army defeat a force of German troops that was coming to the aid of the Huguenots.
After the outbreak of renewed fighting the Huguenots once again called on their German allies for assistance. John Casimir began to raise an army, but this took some time, and so in the autumn of 1575 an advance guard, under the command of Thoré-Montorency, brother of Henry de Montmorency, sieur de Damville (one of the main Huguenot leaders during the Fifth War), began its march across France. Thoré's force consisted of around 1,500 German cavalry, 500 arquebusiers and a small number of French gentlemen.
The Court sent a larger army under Henry duke of Guise into Lorraine (perhaps as large as 10,000 infantry and 1,200 cavalry). Thoré's main aim was to avoid any contact with the Royal army and try and join up with the forces under either his brother Damville or the duke of Alençon.
In an attempt to intercept the Germans Guise left his artillery in Lorraine and moved north to Sedan. The Protestants eluded him and managed to join with a force of 2,000 Picards. Guise pulled back west to Rheims in an attempt to prevent the Germans from crossing the Aisne. From Rheims he called for reinforcements, suggesting that his army was not as large as is sometimes stated. When these failed to arrive he retreated south-west to the Marne, and took up a position between Chateau-Thierry and Epernay.
On 10 October the two armies clashed at Fismes, near Dormans on the Marne. Guise had much the better of the fighting. Although both sides only lost around 50 dead, the Protestants suffered a much larger number of casualties. Part of their force did manage to escape from the trap, crossing the Seine near Nogent-sur-Seine, and Thoré eventually joined up with Alençon at La Châtre, between Tours and Le Mans on the Loir River, some 100 miles to the south-west of Paris.
To celebrate this victory Henry III held a solemn procession and a Te Deum, as well as announcing a new tax, but his mother, Catherine de Medici, realised that the situation was still critical. All of Henry's main opponents were still in the field and the court was desperately short of money. She managed to arrange the truce of Champigny-sur-Veude (21 November 1575) in which most of Alençon's demands were met, but this treaty failed to take hold. The war continued on into 1576 before finally being ended by the Edict of Beaulieu (5 May 1576).