He spent nearly his entire professional career as a partner in the Boston architectural firm of Allen & Collens and its successors.

He enlisted in the American Ambulance Field Service in February 1915, and arrived at the western front, with Section 2, at Pont-a-Mousson, in April 1915.

He was cited July 4, 1915, "for rescue of wounded under fire," offensive Bois-le-Pretre, "Croix de Guerre with Star.

[2] The original indian head was printed on boxes of ammunition marked "Savage Arms Manufacturing Company".

This company was providing ammunition for machine guns used by reconnaissance units and bombers of the French military aviation.

The aircraft was hit numerous times with damage to the engine which forced the pilot to land in German territory near Convensoye, France.

As I neared the ground I had an instant's desire to dive into it — saw a wood in front of me, jumped it and landed instinctively on the crest of a hill.

My machine was a wreck thirty bullets in the fuselage motor and radiator exactly half of the cables cut tires punctured and wings riddled.

Pleasantest are the nights, for one always has vivid dreams of home or the Front You can understand how wearing it is, to be helpless — a sort of living corpse — when there is need of every one.

[1] After several attempts, Willis disguised as a German guard, made his escape from the American camp at Villingen on Oct. 4, 1918, crossing the Rhine river into Switzerland and finally back to Paris.

During his early years with the firm, Willis was chief designer of many of their residential works, most notably the Gloucester, Massachusetts, homes of actor Leslie Buswell and inventor John Hays Hammond Jr., both begun in 1923.

Both houses incorporated extensive architectural salvage: old English and Colonial American for Buswell, and French, Italian and Spanish for Hammond.

[6] Some works in which he had a major role include: Collens, Willis and John D. Rockefeller Jr. revisited Hammond Castle during the planning of The Cloisters in New York City, which incorporated architectural salvage on a larger scale.

[10] During World War II, Willis served in the U.S. Army Air Force as a major in Africa, England and France.

Willis was successful in convincing the U.S. government to transfer 12 Curtiss P-40 Warhawks to the Free French Fighter Group GC II/5 based in North Africa.