The Lochnagar mine was an explosive-packed mine created by the Royal Engineer tunnelling companies, located south of the village of La Boisselle in the Somme département of France, which was detonated at 7:28 am on 1 July 1916, the first day of the Battle of the Somme. The Lochnagar mine, along with a neighbouring mine north of the village known as the Y Sap mine, contained 24 tons of ammonal. At the time these mines were the largest ever detonated.

• http://en.wikipedia.org/wiki/Lochnagar mine