During his 31-year career in the U.S. Army, LTG Blackwell held a wide variety of command and staff positions, including assignment as Deputy Chief of Staff for Operation and Plans, Department of the Army and Commanding General, and 24th Infantry Division. Other key assignments include Deputy Director of Operations, National Military Command Center, Washington, DC; Commanding General, 2d Armored Division (Forward), Garlstedt, Federal Republic of Germany, and Assistant Division Commander, 3d Armored Division, Federal Republic of Germany.

He was a Vice President of Raytheon Company from 2001-2012. He served as VP C3I 2001-2003, VP of Strategic Initiatives for Network Centric Systems 2003-2005, VP of the Rapid Initiative Group, which identified hundreds of millions of dollars in new opportunities for Raytheon while meeting critical customer needs, 2005-2009, and VP of BD for NCS 2009-2012.

Since 2012, General Blackwell has worked as a consultant to the defense industry at The Beacon Group and Accenture and joined BCE in 2024.