War returned in 1792 and would provide a defining backdrop for the rest of Arbuthnot's life. Between 1792 and 1797, and again between 1798 and 1802, a key continental ally for the British in the wars against France was the Austrian Empire. Robert Murray Keith (1730–1795), recently retired from a position as envoy-extraordinary (de facto ambassador) in Vienna, where he had served since 1772, was recalled to head up the British diplomatic mission in Vienna during the build-up to the war. Murray Keith was a family friend, and he invited Robert Arbuthnot to join him as his private secretary.