Siege of Mercq
1405 CE.
Shown on the map at 50.464°, 2.142°.
On 6 May of 1405, a French army under the command of Waleran III, Count of Ligny and Saint-Pol besieged the English castle at Mercq in Pas-de-Calais.
Text from the Wikipedia article Siege of Mercq, licensed CC BY-SA 4.0.