The marketer announced his resignation on his website, stating that it was 'the right time' for him to move on. Bainbridge said he would take a month off before assessing his career options.
While in the role, which he took up in 1999, Bainbridge introduced the Army's youth recruitment programme, called 'Camouflage', which was aimed at 13- to 17-year-olds.
In March, the Army rolled out its celebrity-driven 'To the Best' campaign, with the backing of personalities such as Sir Steve Redgrave, Jonny Wilkinson and Fern Britton.
The Army recently announced it is to increase its investment in direct recruitment marketing to £10m over the next four years. The decision followed the reappointment of Tequila\London to its direct marketing and CRM account.
According to Army research, 27% of its £36m adspend goes toward balancing out the effects of negative media coverage.