Grindall had a late initiation to the Royal Navy, only making lieutenant on 29 November 1776, a full eight years after most of his contemporaries had reached that rank.
Making the most of his unique position, Grindall immediately launched boats and rescued hundreds of struggling survivors in the water, including many from the sinking Achille.
In the week of ferocious storms which followed the battle the sturdy Prince was invaluable, providing replacement stores to more battered ships and towing those that needed it.
Grindall was one of the promoted men who never commanded at sea again, taking a shore appointment in late 1805 and retiring with his family soon afterwards as a vice admiral of the Blue on 31 July 1810, of the White on 12 August 1812, and of the Red on 4 June 1814.
His retirement was a difficult one however, as two of his sons who had joined the navy in their father's footsteps, Edmund and Festing Horatio, died in 1811 and 1812 from unconnected illness.