A soldier who was criticised by superiors who had mistaken him for the only other black sergeant in his wing was racially discriminated against.
Randy Date believed colleagues at the Military Correction Training Centre (MCTC) in Colchester thought he was lazy because of his race, an employment tribunal heard.
Some made rude comments about him after failing to get Phil Collins tickets.
The tribunal upheld one complaint of racial discrimination against him.
Mr Date, who is from Grenada in the Caribbean, had been signed off work suffering from Post-Traumatic Stress Disorder (PTSD) in 2016 before returning to work and transferring to the training wing at the MCTC in April 2017.
The tribunal heard that he did not feel his colleagues adopted a "sensitive attitude" to his sickness.
In an assessment, his reporting officer Flt Lt Taylor said the performance of Mr Date, who is a veteran of Iraq, Afghanistan and Kosovo, was "significantly below par".
He highlighted the sergeant's performance on the Right Turn course as being "badly prepared" despite Mr Date having never taught the course, which was run by the other black sergeant in the training centre.
The tribunal concluded Flt Lt Taylor had not seen the course and was passed information by Sgt Maj Steve Elliott.
On 27 November 2017 a WhatsApp conversation in which fellow non-commissioned officers were complaining about not getting concert tickets, Sgt Maj Elliott said: "Randy Date. He get's [...] everywhere, except work!!!"
The tribunal found that "the claimant's colleagues were discussing the frustrating effect of the claimant's absence on their day-to-day management of work and the WhatsApp message sent by Mr Elliott reflected that frustration".
However, the tribunal found this was not down to racial discrimination.
The level of compensation Mr Date receives is yet to be set and the next hearing is on 12 December.