Shumar was the First Officer aboard Excalibur NX-03 when it was stationed at Starbase 1 unofficially expecting a Romulan attack. When a Romulan fleet did appear, Fleet Captain Erika Hernandez ordered Excalibur to flee and warn Starfleet while she stayed to defend the base aboard Columbia. Excalibur fled, but was too slow to outrun the Romulans. Shumar escaped the ship on a Shuttlepod and later warned Starfleet of the attack, although Excalibur was destroyed. (ST reference: Federation: The First 150 Years)
At some point during the war, he was given command of the SS Intrepid, and lead a fleet into battle against the Romulans in the Battle of Sol. Shumar pressed the attack very aggressively, taking satisfaction in the battle. (ST reference: Federation: The First 150 Years)
- The book Federation: The First 150 Years mentions that Shumar was "newly promoted" to Captain when he was given command of the Intrepid; this contradicts the Starfleet: Year One promotion information.
By 2156, Shumar was commanding officer of the Daedalus-class USS Essex and took part in a war game with one of Enterprise's shuttlepods. This test allowed Starfleet to determine what was wrong with the warp detection grids installed in many star systems. After the war game, Shumar had dinner with the other participants in the game, Captains Archer, Hernandez, Narsu, and Ramirez. (ENT novel: Beneath the Raptor's Wing)
Before he could formally leave the service, however, he was approached by an old friend, Clarisse Dumont, an adviser to President of United Earth Lydia Littlejohn. She convinced Shumar to instead accept a promotion to Captain, and to help guide the nascent Federation Starfleet into a combined military and scientific service.
Shortly after the creation of Starfleet, Shumar was given command of the Christopher-class vessel Peregrine. During this command, he was instrumental in the investigation of the attacks on Oreias V and Oreias VII, determining the human colonists there had inadvertently disturbed the sacred burial grounds of the alien Nisaaren. (ST novel: Starfleet: Year One)