Losing his wife and child in the Great Famine, he immigrated to the United States in 1850.

[1] After the American Civil War began, McCleave was named Colonel and was ordered to recruit a cavalry regiment in California.

However, only a battalion of five companies could be organized at that time and he was made a captain in what would eventually become the 1st California Cavalry Regiment instead.

He was promoted to major in January 1863 and spent the rest of the war fighting Indians in New Mexico.

There he dealt real estate and commanded the Veterans Home of California Yountville.