At which battle were tanks first used in combat?

Tanks were first used in combat at the Battle of Flers–Courcelette. The battle began on 15 September 1916 as part of the larger Battle of the Somme during the First World War.

Britain deployed Mark I tanks in support of its infantry attack against German positions. Their mechanical unreliability and limited numbers reduced their immediate impact, but the appearance of the vehicles marked the first battlefield use of tanks.

The broader answer “Battle of the Somme” is sometimes used because Flers–Courcelette was one phase of the Somme Offensive. However, Flers–Courcelette is the more precise battle name and is the canonical answer when asking where tanks first entered combat.

The later Battle of Cambrai in 1917 was the first major operation to employ tanks in large numbers and as part of a more developed combined-arms plan.