Private First Class Gillett was a member of the 2nd Engineer Combat Battalion, 2nd Infantry Division. On 2 September 1950, enemy forces overran three infantry battalions, the 2nd Engineer Battalion, was rushed into line to serve as infantry and to protect the vital communications center of Yongsan, South Korea. The enemy was repulsed but Private First Class Gillett was killed during the defense.

Gillett was awarded the Purple Heart, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.