Verbeck was born in Nagasaki, Japan, on January 18, 1861, the son of Guido Verbeck and Maria Verbeck (née Manion).
His father worked in Nagasaki as a missionary and educator for the Dutch Reformed Church.
He was one of six brothers and three sisters.
His brother was the cartoonist, Gustave Verbeek.

In 1879, at the age of 18, Verbeck emigrated to the United States.
He enrolled in the California Military Academy.
He served in the Fifth California Infantry, rising to the rank of major.
Verbeck was born in Nagasaki, Japan, on January 18, 1861, the son of Guido Verbeck and Maria Verbeck (née Manion). His father worked in Nagasaki as a missionary and educator for the Dutch Reformed Church. He was one of six brothers and three sisters. His brother was the cartoonist, Gustave Verbeek.
In 1879, at the age of 18, Verbeck emigrated to the United States. He enrolled in the California Military Academy. He served in the Fifth California Infantry, rising to the rank of major.
William Verbeck