E5 experienced an engine room explosion on 8 June 1913, twenty days before commissioning, which resulted in thirteen deaths.

A further three men were killed when there was an oil blow back into the starboard engine off St Ann's Head.

The submarine depot ship HMS Adamant and Alligator carried the medical team out to meet E5 on her way into Pembroke Dock.

In December 1913, E5 was part of the 8th Submarine Flotilla, based at Portsmouth as part of the Home Fleets[4] When war was declared with Germany on 5 August 1914, E5 broke off a refit to re-join 8th Submarine Flotilla at its war station in Harwich later that day.

[5] The 8th Submarine Flotilla, including E5 was assigned to patrol in the east end of the English Channel during the passage of the British Expeditionary Force to France in early August.

German trawlers and aircraft drove off E5, allowing the damaged Schwarzwald to safely make port.

The German airship dropped bombs on the British submarines, while E5 fired on L9 with her deck gun.

Another theory attributed her loss to depth charge attack by torpedo boats escorting the battlecruiser Seydlitz.