Lorettoschlacht
The unit was employed under the command of I Corps and the Indian Corps on operations in preparation for the Battle of Aubers Ridge on 9 May 1915, which formed part of the British contribution to the Second Battle of Artois (9 May – 18 June 1915). The Battle of Aubers Ridge marked only the second British use of specialist tunnelling companies, who tunnelled under no man's land and planted mines under the German defences to be blown at zero hour. 173rd Tunnelling Company was also extended to the "Rue du Bois" and "Red Lamp" areas soon afterwards.