Sive graduated from Brooklyn College with a degree in political science in 1943. He had enlisted in the U.S. Army in 1942 and was called up in the spring of 1943 shortly before his college graduation. He served in the front lines in Europe, including in the Battle of the Bulge, was wounded twice and awarded the Purple Heart with Oak Leaf Cluster. Convalescence at a U.S. Army hospital in Devon, England gave him further opportunity to study the verse of William Wordsworth.