171st Tunnelling Company
…combined load of 146,000 pounds (66,000 kg) of ammonal, formed part of the mine galleries that were dug by the British 171st, 175th, 250th, 1st Canadian, 3rd Canadian and 1st Australian Tunnelling companies as part of the prelude to the Battle of Messines (7–14 June 1917), while the British 183rd, 2nd Canadian and…