He accidently drowned in Platte River returning from his mission.
The Sims family traveled to the Salt Lake Valley with the Jacob Gates Company in 1853. The family included George and Caroline HIlliker, and their children Emma Maria Hilliker and Julia Hester.
At the end of a mission to England, George traveled home with the William S. S. Willes Company in 1865. He died en route by drowning in the Platte River.
His surname is spelled "Simms" on the missionary register.