Mount Tumbledown, Mount William, and Sapper Hill lie west of Stanley. They were held by BIM-5, a reinforced, cold weather trained and equipped, marine battalion. During preparations for movement to the Falklands, the Marine battalion was brought up to full strength of a light brigade with a company of the amphibious engineer company and a battery of the 1st Marine Artillery Regiment. The 5th Marines were further strengthened by three Tigercat SAM/Hispano-Suiza 35mm batteries of the 1st Marine Anti-Aircraft Regiment, deployed along Stanley harbor, and a heavy machine-gun company of the Headquarters Battalion.