"At the Battle of Fontenoy in 1745 two regiments, one English and the other French, met unexpectedly face to face at the crest of a hill. In the best sporting traditions, the English commander offered his French adversary the first shot. But the commander of the French troops did not wish to be outdone in battlefield manners and insisted that the British fire first. Which they did, decimating the French line in the process"

Source "Everlasting Gaffes of the Famous"

Sometimes manners aren't the best thing to have.