William McKinney went overseas as a soldier in 1942 and served in action in Normandy and Holland. He rose to the rank of captain and was mentioned in dispatches. In addition to his war service, he served in different capacities in the Reserve Army (Militia) continuously since 1949.

He was appointed to the rank of Honorary Lieutenant Colonel of the Royal New Westminster Regiment from 1972 until 1981 when he became the Honorary Colonel of the Regiment. He also served his community in many ways throughout his life – for example, President of the BC Canadian Diabetes Association, the New Westminster Lions Club, the New Westminster YMCA, to name but a few examples.