From January to April 1944 Heaney attended the United States Army Command and General Staff College in Fort Leavenworth, Kansas. Afterwards she carried out administrative work on a posting to British East Africa. From 1946 she served in Mandatory Palestine, a posting that included the period of the 1947-48 civil war. Heaney transferred from her war substantive commission to a permanent commission on 1 January 1947 and was promoted to junior commander (equivalent to captain) the following month. On 20 March 1947 she was awarded the Efficiency Medal for long service, at which point she held the rank of temporary senior commander (equivalent to major).