In March 1941, the heavy cruiser had encountered a tanker supplying a possible raider, which split up and fled when ordered to stop. "Canberra" pursued the suspected raider, and fired from maximum range to avoid retaliatory fire, while her Walrus amphibian attempted to stop the tanker with bombs. The cruiser fired 215 shells, with most missing, while all of the Walrus' bombs were used. However, both ships (the raider supply ship "Coburg" and the captured Norwegian tanker "Ketty Brovig") had commenced scuttling once "Canberra" started firing. Post-action analysis found that if "Canberra" had moved closer, the same damage could have been achieved for less ammunition, and one or both ships might have been captured: factors that Burnett had commented on during his previous posting as Deputy Chief of Naval Staff, and which Frame and Gill think may have influenced his actions.