[2] James and Minnie Simon's marriage produced four children: Sidney A., Helen Judith, Leon Jacob, and David Irving.

[5][6] After World War II, Simon studied and attended classes at the Académie de la Grande Chaumière, in Paris, France.

At age 25, then stationed at Fort Belvoir, Virginia, Simon's art talent was recognized and he was tasked with heading and developing a special service branch referred to as [the] Morale Division.

[8] It was while Simon was stationed at Fort Belvoir that he met and worked with fellow soldier Willard W.Cummings,[8] who was also part of this Morale Division art detail.

[9] From March 1943 – October 1945, Captain Simon served as an American official war artist and was assigned to General Douglas MacArthur's headquarters.

Simon was chosen to paint the formal surrender ceremony as witnessed September 2, 1945, in Tokyo Bay aboard battleship USS Missouri.

In 1946, Simon, along with artists Willard W. Cummings (1915–1975), Henry Varnum Poor (1888–1971), and Charles Cutler (1914–1970), developed and founded The Skowhegan School of Painting and Sculpture located in Madison, Maine.