In the wake of the initial landings came many supporting units. Among the first was No. 6 Wireless Unit RAAF, an intelligence unit responsible for intercepting and decoding Japanese signals.
By 24 October it was clear that Japanese forces were heading to attack the allied ships and forces at Leyte. HMAS Shropshire and HMAS Arunta were part of two task groups taking up position at the northern entrance to Surigao Strait. They awaited the arrival of the Japanese. The night was clear and dark, and the sea calm.
On 25 October, 11 destroyers despatched southward to attack the approaching Japanese force. They broke into two sections, one of which was under the operational tactical command of Arunta.
The open fire phase lasted less than 20 minutes. This was the last time battleships were utilised in a tactical battle line. Suddenly all was quiet in Surigao Strait. What remained of the retreating Japanese force was subjected to further attacks by ships, including Shropshire and Arunta, and aircraft as they fled. The Japanese surface fleet was crippled, giving the Allies a decisive victory.