1915 – Breadner entered military service with the Royal Naval Air Service.

         – Breadner left the family business in Ottawa to enlist in the Royal Naval Air Service.

1922 – After the conclusion of World War One, he left the military and he joined the Canadian Air Force.

1924 – Breadner was one of the first to offer his services and was assigned as commander of Camp Borden, the RCAF training camp.

1928 – He was appointed Director of the RCAF under Lindsay Gordon.

1936 – Breadner received training at the Imperial Defence College.

1940 – Air Commodore Breadner was appointed Chief of the Air Staff.

         – He succeeded G.M. Croil as Chief of Air Staff on May 29th.

1943-1945 – Air Marshal Breadner was re-assigned to the position of Commander-in-Chief of the RCAF overseas, a post he held until his retirement at the rank of Air Chief Marshal, the only Canadian to ever be promoted to such rank.