Captain Sir Henry Seton, of Abercorn and Culberg - gazetted a captain in one of three Additional Companies on July 17, 1757 - bringing the total companies in the 78th's establishment up to thirteen.  Ian McCulloch notes that Captain Seton's company went to Halifax but remained there in garrison on guard duty as they were considered not to be sufficiently trained for the Louisbourg expedition.  Seton's company rejoined the battalion on its way back to Boston and marched across Massachusetts to spend the winter in Schenectady in the Mohawk River Valley.  In the spring of 1759, Sir Henry transferred [22 April 1759] out of the 78th into the 17th Foot (Monckton's) which formed part of Amherst's successful expedition against Ticonderoga and Crown Point, while the 78th went via Halifax and Louisbourg to join Wolfe's expedition against Quebec.  The following year, Sir Henry's new regiment went north to Montreal via Crown Point with Havilland's expedition to take Montreal.  In 1761 his company of the 17th was one of two assigned to Lt Col James Grant's 1761 expedition against the Cherokee which was successful.  Sir Henry then subsequently fought in the Caribbean at Havana and left on half-pay in 1763 at the end of the war.  He married Margaret Hay of Drummelzier (1770) and died in June 1788.  Sir Henry was the Captain of the Royal Edinburgh Company of Golfers for 1756.