Robert April served as Federation Ambassador-at-large- after his five year command of the USS Enterprise.
Ambassador-at-large was a Federation position that Commodore Robert April held for around twenty years following his service as Captain of the USS Enterprise. April maintained this position as he neared mandatory retirement age, but due to his actions aboard the Enterprise as acting captain following the de-aging of the entire crew, the Federation was willing to hear his appeal to continue. (TAS: "The Counter-Clock Incident")