Reginald Dimsdale was born on 25 December 1885, the son of Charles, Seventh Baron Dimsdale (of the Russian Empire) of Messenden Manor, Buntingford, Hertfordshire and Alice, Daughter of Charles James Monk.  

He joined the Royal Navy as a Cadet in 1901 and as a Midshipman was appointed to HMS CORNWALLIS in 1905.  As a Sub Lieutenant, Reginald Dimsdale joined the Submarine Depot Ship HMS FORTH at Devonport in 1907 ‘for Submarine Training’. Promoted to Lieutenant in 1908, in 1909 he was appointed to the Submarine Depot Ship HMS ONYX ‘for Submarine A9 in Command’ and the following year he took command of HMS C8. His next appointment was in command of HMS C15 in  1912.

In 1914 he was appointed to the cruiser HMS ARGYLL for his ‘Big Ship’ time. After leaving HMS ARGYLL in 1915 he returned to submarines to command HMS C21 followed by command of HMS D3.

Reginald Dimsdale was re-appointed in command of HMS E22 on 24 April 1916. On 25 April, E22 was on patrol in the North Sea when she was hit and damaged by a single torpedo fired from the German U-Boat UB-18. E22 sank immediately and there were only two survivors out of the crew of thirty-three. Lieutenant Dimsdale was not one of them. 

Reginald Dimsdale is commemorated on the Portsmouth Naval War Memorial on Panel No. 11.