David Croft was born at the New Berlin colony on Earth's moon, which partly accounts for his height. His parents were astro-biologists who when Croft was born where the chief scientists on at the medical research facility at New Berlin. However, the life of an astro-biologist is rarely stable and within two years of Croft's birth, the entire family was moved onto a research vessel.
Croft's parents were killed by a Dominion vessel in 2370 whist exploring the surface of a planet in the Gamma quadrant. Croft was already in his third year at Starfleet Academy, but when he learnt of his parents death, he immediately wanted to take out his revenge on the Dominion.
Instead of continuing his education at Starfleet, he left and joined the Federation Marines. After six months basic training and with the start of the Dominion war, Croft soon had the opportunity to pay the Dominion forces back. David fought in many battles during the war and received both injuries and medals for his actions. Providing to be a born leader, he quickly rose up the ranks.
Whilst at Starfleet Academy, David had been working towards becoming a pilot and at the end of the Dominion war, he returned to Mars and undertook the flight training programme. Once complete, he was proficient in flying all the vessels operated by the Federation Marines, from the light Hammer-Head fighter, to the heavy transporters such as the Hawke and Rhino vessels. In 2383, Croft was re-assigned to be a test pilot for the new Yellowjacket fighter that was being developed for the Marines.
The first battlefield test of the Yellowjacket occurred in January 2384 when the first squadron of Yellowjacket fighters were deployed from the Marine carrier Nimitz, during the Barien war. During the battle, Croft's fighter was hit several times and David was forced to land on a Barien occupied planet. He battled through the occupied territory and was eventually picked up by a Nuan military transport. Although most of his injured were treated successfully, Sam lost his left eye.
Now rather than have a cybernetic replacement, Croft has elected to wear an eye patch. This decision has however meant that he can no longer be an pilot. He instead took the officers programme and six months later was assigned a new platoon, eventually rising to the position of Command Marine on the USS Grant Lee.
In January 2387, he was re-assigned to the Marine FARP on Serenity as the CO.