"Canopus" and "Glasgow" returned to Stanley, arriving there on 8 November 1914; they immediately proceeded to join the British warships concentrating off the River Plate. "Canopus" was ordered to return to the Falklands and place herself in Stanley to guard the port on 9 November. She arrived three days later, and began to make preparations for the defence of the harbour. At Stanley, "Canopus"s crew set up defences against an attack by Graf Spee. "Canopus" herself was beached in the mudflats in a position that allowed her to cover the entrance to the harbour and have a field of fire landward to the southeast; to reduce her visibility, her topmasts were struck and she was camouflaged. An observation post was established ashore on high ground and connected to the ship by telephone, allowing "Canopus" to use indirect fire against approaching ships. Some of her 12-pounder guns and a detachment of seventy Royal Marines were put ashore to defend Stanley and its environs. On 25 November, "Canopus" intercepted a radio message that indicated that Spee's squadron had rounded Cape Horn, though the message was erroneous; Spee actually made the passage on the night of 1–2 December. By 4 December, "Canopus"s crew had completed their preparations.