Although his regiment served in the War of Jenkins' Ear and the War of the Austrian Succession, he did not accompany it. He became Lieutenant General in 1743, based on time served; this made him eligible for command, but there were far more generals than positions and many never held an active post. When the Jacobite rising of 1745 began in August, most of the regular army was in Flanders; Handasyd was sent to the border fortress of Berwick-upon-Tweed, which became a key position after the government defeat at Prestonpans in September. When Sir John Cope arrived in Berwick , he was relieved of command and as senior officer, Handasyd became Commander-in-Chief, Scotland. General Wade, commander at Newcastle, instructed him to establish a supply base at Berwick and obtain information on rebel movements.