A Washington, D.C. native and Gonzaga College High School graduate (inducted into the Gonzaga Athletic Hall of Fame in 2010), Major General Ewers was commissioned a Marine second lieutenant in 1984 and certified as a judge advocate in 1986. As a junior officer, he served as a prosecutor, defense counsel, Special Assistant U.S. Attorney, Deputy Staff Judge Advocate, military justice officer, installation law officer, staff secretary, and as a recruit training series commander. From 1996 to 1999, he was a military judge on the Sierra Judicial Circuit, Navy-Marine Corps Trial Judiciary, presiding over more than 500 courts-martial.

From 2000 to 2002, then-Lieutenant Colonel Ewers was the Officer in Charge, Legal Service Support Section, 1st Force Service Support Group – the busiest military justice section in the armed forces – and was responsible for developing the legal service support plan for I Marine Expeditionary Force (I MEF) for the invasion of Iraq. In 2002-03, he served as SJA, 1st Marine Division, and participated in the invasion. After returning from Iraq, he served as Commanding Officer, Third Recruit Training Battalion, MCRD, San Diego. While in command, Major General Ewers was selected for colonel and, in turn, selected as a CMC Fellow at the Center for Strategic and International Studies where he was assigned during the 2004 - 2005 academic year.

In August 2005, Major General Ewers assumed duties as SJA, I MEF, and soon thereafter was assigned to work economics and governance issues for I MEF (Forward), serving as Deputy Team Leader, Al Anbar Provincial Reconstruction Team, in 2006-2007. Returning from Iraq in February 2007, he resumed his duties as I MEF SJA until moving back to the judiciary in August 2008 as Circuit Military Judge, Western Judicial Circuit. From April 2010 until August 2011, he was the Deputy SJA to the Commandant of the Marine Corps before serving as the Department of the Navy’s Assistant Judge Advocate General for Military Justice. On 2 July 2014, Major General Ewers was promoted to his current rank and assumed the billet of SJA to the Commandant. He retired from that billet on 1 September 2018.

Major General Ewers received a B.A. in philosophy/political science from the University of Delaware (home of the Fightin' Blue Hens) in 1981, a J.D., cum laude, from Georgetown University Law Center in 1985, and a Master of Laws as an honor graduate of the Judge Advocate General School, U.S. Army, in 1994. He is also a distinguished graduate of the Marine Corps Command and Staff College (2000). Major General Ewers' military decorations include the Distinguished Service Medal, Legion of Merit (with three stars), Bronze Star, Meritorious Service Medal (with three stars), Navy-Marine Corps Commendation Medal, Navy-Marine Corps Achievement Medal, Combat Action Ribbon, Purple Heart and the Drill Instructor Ribbon. He is married to the former Elisa Catalano and has two sons, John Scalley Ewers and Lloyd Wills Ewers.