The Somme featured prominently in several historical campaigns. In 1066, the invasion fleet of William the Conqueror assembled in the Bay of the Somme, at Saint-Valery-sur-Somme. The river also featured in the 1346 withdrawal of Edward III of England's army, which forded the river at the Battle of Blanchetaque during the campaign, which culminated in the Battle of Crécy. Crossing the river also featured prominently in the campaign which led to the Battle of Agincourt in 1415.
In 1636, a Spanish army led by
Thomas Francis, prince of Carignan, crossed the Somme defeating a French army during the Thirty Years War threatening Paris.
Most famously, the Battle of the Somme, during World War I, lasted from July to November 1916 and resulted in more than a million casualties. Private A S Bullock in his wartime memoir recalls his first sight of it in early April 1918: '... we reached a small place called Hengest sur Somme. The train stopped and we descended. There in front of us was a muddy, sluggish and somewhat narrow stream, which has given its name to one of the most awful battles in history - the Somme.'  The great battles that finally stopped the German advance in the Spring Offensive of 1918 were fought around the valley of the Somme in places like Villers Bretonneux, which marked the beginning of the end of the war.