Jack McKinnon's life in Santa Cruz County, California, remains a mystery. He was born on March 9, 1948, in Santa Cruz; however no record of his family, formative years or life in the county has been located.

During the early part of 1967, McKinnon was apparently living in Santa Cruz County and was drafted into the US Army. As an entering recruit he would likely have spent the eight-week basic training course at Fort Ord, California, or Fort Lewis, Washington, with an additional five weeks of advanced individual training to prepare him as an infantryman.

Private McKinnon arrived in Vietnam on April 13, 1967, and joined Company D, 4th Battalion of the 31st Infantry Regiment. That unit was in the process of moving from Tay Ninh to Chu Lai on the South China Sea to participate in Operation Oregon, which was a sweep into Binh Son Province.

About 1967 McKinnon was promoted to specialist fourth class and likely participated in additional combat operations in Quang Ngai, Chu Lai, and Que Son Valley. It was probably at one of these locations that Specialist Fourth Class Jack Wiley McKinnon Jr. was killed in action on January 3, 1968, while attempting to prevent Viet Cong guerillas and the North Vietnamese Army from capturing the coastal lowlands.

His body was recovered, returned to California and was interred in the Golden Gate National Cemetery.

(CBR; VVMW; Global Security.org, 4th Battalion 31st Infantry Regiment http://www.globalsecurity.org/military/agency/ army/4-31in.htm, [16 September 2008], 196th.Org, Untitled Document, http://www.196th.org/guestbook/Guestbook2005/ Guestbook2005archive.htm, USDVA)