Born in
Sibley, Iowa to Nellie (
née Walker) and John Thomas Grow. His mother died when he was two years old and Grow went to live with his paternal grandparents, as his father went to
Canada to work. He graduated from the
University of Minnesota in 1916. He married Mary Louella Marshall (1896–1974), daughter of Willamina H. "Willie" (
née Robertson) and J Walter Marshall, of
Cleveland, Tennessee on November 5, 1917, in Hamilton, Tennessee. They had two sons, Robert Marshall and Walter Thomas, both attendees of the
United States Military Academy at
West Point, New York. They had an additional child die as a one-day-old in
Brownsville, Texas. Grow joined the
Minnesota National Guard in February 1914, whilst attending the University of Minnesota, and was
commissioned as an officer in November 1915. On December 5, 1916, he was promoted to
first lieutenant. April 1917 saw the
American entry into World War I and Grow was promoted again, this time to
captain, in the
National Army on August 5, 1917. On October 12, he transferred to the
Regular Army but retained his captain rank. Grow did not see active service during
World War I. He remained in the army during the
interwar period, attending both the
United States Army Command and General Staff College and the
United States Army War College. Robert W. Grow was the commander the
6th Armored Division on the
Western Front, fighting during the
battles of Normandy and of
the Bulge. His command of the 6th Armored Division in its rapid assault across the Brittany Peninsula is considered one of the finest examples of armor in the exploitation phase. This stunning advance is often overlooked due to the more glamorous exploits of the rest of the U.S. Army surrounding the German Seventh Army at the same time. ==After the war==