Complex sentence: General George Marshall, Chief of Staff of the United States Army, accepted the suggestion for Project Plough and since no suitable vehicle existed, in April 1942 the US government started asking automobile manufacturers to look into such a design.
Split into simpler sentences: General George Marshall, Chief of Staff of the United States Army, accepted the suggestion for Project Plough. In April 1942, since no suitable vehicle existed, the U.S. government asked automobile manufacturers to look into such a design.