Bowyer subsequently transferred to the ship of the line HMS "Lancaster" on 12 November and then to the ship of the line HMS "Royal Anne" on 20 April 1757 in which he took part in the Raid on Rochefort in September while serving in the English Channel. He passed his exam for lieutenant on 6 February 1758 and was promoted to that rank on 13 February and sent to the West Indies to serve on the ship of the line HMS "Nottingham" as her third lieutenant. As such he fought at the Siege of Louisbourg between 6 June and 27 July, before becoming the second lieutenant of "Nottingham" on 25 August. On 31 January 1760 he left "Nottingham" to re-join his mentor Howe on the ship of the line HMS "Magnanime" as her fourth lieutenant.