[7] During the Second Boer War, he fought as a captain in an Australian regiment, the Prince of Wales' Light Horse, and received the Queen's South Africa Medal with three clasps.
[3][8] After the Boer War, Kennedy moved to the United States, living in Wyoming through about 1910, and then in Nevada, Missouri and Davenport, Iowa.
In November 1914, on the outbreak of World War I, he returned to Great Britain and joined the Ayrshire Yeomanry in January 1915.
[5] Kennedy made a second marriage to Helen Ethel McDouall, widow of Richard John Cuninghame, of Hensol House, on 26 April 1933.
In 1945 he presented the family seat, Culzean Castle, to the National Trust for Scotland under the Country House Scheme.