Battle of the Somme
The first tank was called 'Little Willie', and it had a crew of three men.  The maximum speed that it could travel was three mph and it was not able to cross the trenches.  The first tank battle, Flers-Courcelette named after the two villages that were the objectives for the attack, started on 15 September 1916.  Out of the 49 tanks that should have been there only 36 arrived.  This was the first time that tanks had been used in World War I, but because they were only armed lightly and the mechanics of them often went wrong they did not make a great impact.  However, casualties were low in the tank crews.