Marcus McManus was a Starfleet physician serving during the 24th century.
Born in Ireland in2341 on a small farm in the McManus family since the 1400s, he was a rough and tumble child who would disappear for long periods of the day with a couple of hound dogs for company.
He graduated Veterinary School and practiced for two years from his family's farm but wasn't satisfied. Going through an arduous process he was accepted into the Starfleet Medical Academy. After graduation he applied to serve in the Fleet Marine Force, providing medical treatment to Marines in the field.
As a freshly mintedLieutenant Junior Grade, he reported to the USS Normandy as a surgeon attached to the11th Marine Expeditionary Unit's CASH. The ship left for a seventh-month presence patrol of the Federation's Demilitarized Zone border. The Marine unit participated in several training scenarios, including planetary invasion, ship boarding and space station seizure, and other evolutions intended to let the Cardassians know they were ready to act on any hostile actions. The ship also visited Prophet's Landing and two other Bajoran colonies.
After the tour he transferred to Starbase 375 as part of the Fleet Surgical Team, a medical team ready to respond to numerous situations.
The team was on hand to provide medical aid when refugees fled the Dominion's massacres in the Demilitarized Zone.
When hostilities with the Dominion broke out the 26th Marine Expeditionary Unit and was on the frontlines of the Dominion War. The constant death wore him down, and by the end of the war, he was drinking himself to sleep each night.
After the war, he attempted to resign his commission but was convinced to stay in the service and was transferred to Starbase 45 as Chief Surgeon with a promotion to Lieutenant Commander.