Shortly after the death of Albert Mountain Horse, his older brothers Mike and Joe enlisted in the First World War. Albert had died one day after his return to Canada on 19 November 1915. He was hospitalized because of gas poisoning and, with acute respiratory distress, contracted tuberculosis.

Mike was buried alive for four days at Cambrai in October 1917, for which he was hospitalized for shell shock. He returned to action, was wounded twice, became a sergeant and won the Distinguished Conduct Medal for bravery.

Mike Mountain Horse Elementary School was named in honour of Mike in 1986.