His parents were Anna Louisa, née de la Hooke (1824–1907) and Alfred William Otter (1815–1866),[1] both English immigrants who married in Ontario on 15 September 1842.

On May 2, 1885, he led a Canadian force of more than 300 in the Battle of Cut Knife against a Cree and Assiniboine camp defended by Poundmaker and Fine-Day.

During the Second Boer War, Otter, by then a lieutenant colonel, commanded the 2nd (Special Service) Battalion of The Royal Canadian Regiment of Infantry in South Africa.

Otter had the reputation of being something of a martinet – due mainly to his desire that the young Canadian Army should not show up badly when compared to British troops.

[2] He wrote The Guide: A Manual for the Canadian Militia (Infantry) Embracing the Interior Economy, Duties, Discipline, Drills and Parades, Dress, Books, and Correspondence of a Battalion with Regulations for Marches, Transport & Encampment, Also Forms & Bugle Calls in 1914, which includes sections on discipline, courts martial, offences, complaints, and defaulters.

Without this work of the Otter Commission the CEF and its achievements would have had no continuance with existing units of the Canadian Army today.