MI5 started in 1909 in World War I

It successfully broke up the German spy network

in the UK on the eve of the declaration of war.

During the war, a further 35 spies were captured. Several were executed, with the rest being

imprisoned or interned.

In 1909, the Committee of Imperial Defense reviewed Britain's defenses against espionage, focusing

particularly on the danger to British naval ports from

German spies.

The War Office and Admiralty agreed to jointly establish a

Secret Service Bureau to coordinate intelligence work.

Captain Vernon G.W. Kell of the South Staffordshire Regiment and Captain Mansfield Cumming of the Royal

Navy were nominated to head the new Bureau, which was established in October 1909.

https://www.mi5.gov.uk/output/1909-to-world-war-1.html

http://www.fas.org/irp/world/uk/mi5/index.htmldigitaleconomybill.blogspot.com

http://bhtimes.blogspot.com/2007_09_05_archive.htmlhttps://www.mi5.gov.uk/output/origins.html

http://www.history.navy.mil/photos/events/ev-1900s/gw

f07-09/gwf-11a.htm