In 1753, French troops from Canada marched south and seized and fortified the Ohio Valley. Britain protested the invasion and claimed Ohio for itself. On May 28, 1754, the French and Indian War (the North American theatre of the Seven Years' War) began with the Battle of Jumonville Glen. French Officer Ensign de Jumonville and a third of his escort was killed by a British patrol led by George Washington. In retaliation the French and the Indians defeated the British at Fort Necessity. Washington lost a third of his force, and surrendered. Major General Edward Braddock's troops were defeated in the Battle of the Monongahela, and William Johnson's troops stopped the French advance at Lake George.