The British E-class submarines started out as improved versions of the British D-class submarine. The E class served with the Royal Navy throughout World War I as the backbone of the submarine fleet. The last surviving E class submarines were withdrawn from service by 1922.

The D-class submarine was the Royal Navy's first class of submarines capable of operating significantly beyond coastal waters. They were also the first boats to be fitted with wireless transmitters. Ten were laid down between 1907 and 1910, though only 8 were completed as D-class boats. The final two hulls were completed as British E-class submarine.