Who did Donald's grandfather body guard for?

Context: Ross was born in Nairn, in Middlesex County, Ontario, the son of Donald Ross and Margaret Halbert. His grandfather was part of Duke Wellington's body guard at Waterloo, and was an escort to Napoleon Bonaparte on his exile to St. Helena. Ross was educated at Nairn Public School, and moved to Manitoba in 1874, where he worked on the first telegraph line. In 1877, he established a real estate business. Ross served on the Winnipeg City Council for eight years, the Winnipeg School Board for twenty-three years, and the Winnipeg Public Parks Board for eleven years. In 1880, he married Margaret McIvor.

Answer: Donald's grandfather was a body guard for Duke Wellington.