Complex sentence: Initially tasked with defending Townsville against possible invasion from the Japanese, in March 1942, the brigade's three infantry battalions--the 15th, 42nd and 47th Battalions--began concentrating in Townsville where they formed part of the 5th Division.
Split into simpler sentences: Initially tasked with defending Townsville against possible invasion from the Japanese. In March 1942, the brigade's three infantry battalions--the 15th, 42nd and 47th Battalions--began concentrating in Townsville where they formed part of the 5th Division.