His reporting career officially began when he took a part-time job at the radio station WEMP, which eventually became a full-time position.
Due to his broadcasting experience, he became a U.S. Army combat war correspondent, where he worked alongside Edward R. Murrow and Eric Sevareid.
He was a regular correspondent on NBC's "Army Hour",[3] filing reports from North Africa, Sicily, Italy (including the liberation of Rome), France and Germany during WW2.
During that time he co-created and produced the war documentary television series The Big Picture, appearing in several episodes as a narrator or presenter.
'[2]After the war, Zimmerman again returned to WEMP, then worked brief stints at WFOX and WRAC before WITI hired him as news director in 1959.
He remained at WITI until his retirement in 1986, although he still occasionally served as a reporter emeritus and as a mentor to some of the younger staff at the station.
[2] In 2011, he took part in the Stars and Stripes Honor Flight to Washington, D.C.[5] He also won the Alfred P. Sloan Foundation award for creative editorial writing.[1][when?]