The Battle of Mars-La-Tour was fought on 16 August 1870, during the Franco-Prussian War, near the village of Mars-La-Tour in northeast France. One Prussian corps, reinforced by two more later in the day, encountered the entire French Army of the Rhine in a meeting engagement and, surprisingly, forced the Army of the Rhine to retreat toward the fortress of Metz.
A cavalry patrol of the 1st Squadron of the 1st Hanoverian Dragoon Regiment No. 9, led by Rittmeister Oskar von Blumenthal, discovered that Marshal François Bazaine's 160,000-man Army of the Rhine was attempting to escape from Metz to join with French forces at Verdun. This intelligence prompted General Prince Friedrich Karl, commander of the Prussian Second Army, to order at 1900 on 15 August a grossly outnumbered group of 30,000 men of the advanced III Corps under General Constantin von Alvensleben to cut off the French line of retreat at Mars-la-Tour and Vionville.
At 0900 on 16 August, they engaged the French army near Vionville, east of Mars-la-Tour. III Corps routed the French 2nd Army Corps and captured Vionville at 1130, blocking any further escape attempts to the west.