On 27 August 1940, Richards joined the Second Australian Imperial Force (AIF), and was allotted the AIF service number NX70273. He was appointed Regimental Medical Officer of the &lt;a href="2/15th%20Field%20Regiment%20%28Australia%29"&gt;2/15th Field Regiment&lt;/a&gt;, an artillery unit of the ill-fated 8th Division, on 18 November 1940, and embarked for Singapore with his unit on 29 July 1941. During the Malayan campaign, Richards coordinated the medical care for his unit, which fought gallantly but unsuccessfully to stem the Japanese advance on Singapore. He became a prisoner of war of the Japanese when Singapore fell on 15 February 1942.