The appointment of Lt. Gen. H.R. McMaster to serve as President Trump's national security adviser has created a vacancy at the top of the Army Capabilities Integration Center, which is charged with defining the Army of the future. In his capacity as ARCIC director, McMaster has championed modernization of the Army's combat vehicle fleet, repeatedly challenging arguments about cost by emphasizing the critical need of a capable maneuver force. In December, he highlighted the array of problems facing the service:...