When the TF was mobilised on the outbreak of war in August 1914, the Durham Fortress Engineers took up their places in the North Eastern Coastal Defences. At first they were employed on constructing field defences, erecting hutted camps,
etc. By the summer of 1915 there were three strong lines of entrenchments, bomb-proof shelters and dug-outs linking strongpoints and gun positions along the coast as well as the fixed defences at Tynemouth and Hartlepool. In August 1916 the Durham Fortress Engineers overcame shifting sand dunes to construct Link House Battery to defend
Blyth Harbour. Although the coastal towns of NE England were bombarded by the German Navy on 16 December 1914 (
Raid on Scarborough, Hartlepool and Whitby) and by
Zeppelins in January and June 1915, it became clear that a fullscale German invasion of Britain was unlikely, while the armies in the field required large numbers of engineers. The Fortress Engineer units therefore began organising field companies for overseas service. The Durham Fortress Engineers found three field companies, while the remainder of the unit continued to be employed around the Tyne Garrison. These companies were numbered 1st to 3rd (or formally 1/1st to 1/3rd, since they were composed of '1st-Line' Territorials who had volunteered for overseas service) and went to France in September 1915. A 530th (Durham) Reserve Field Company was also formed, from 2nd or even 3rd Line Territorials. This did not proceed overseas, and was probably quickly absorbed into the central training organisation.
1st Durham Field Company 1st Durham Field Company joined
4th Division in France on 20 September 1915 and served with it on the
Western Front to the end of the war. It was renumbered 526th (Durham) Field Company, RE, in February 1917.
2nd Durham Field Company 2nd Durham Field Company joined
5th Division in France on 20 September 1915 and served with it on the Western Front until November 1917, when the division was transferred to the
Italian Front. 5th Division returned to the Western Front in April 1918 and fought there until the end of the war. It was renumbered 527th (Durham) Field Company, RE, in February 1917.
3rd Durham Field Company 3rd Durham Field Company landed at Le Havre on 18 September 1915 and joined
51st (Highland) Division on 19 September, during the latter part of the
Battle of the Somme. On 30 January 1916 it transferred to
7th Division (in exchange for a Highland Field Company) and served with it on the Western Front until November 1917 when the division was transferred to the Italian front. 7th Division then served in Italy until the end of the war. It was renumbered 528th (Durham) Field Company, RE, in February 1917. ==Inter-War period==