In 1914, the General Headquarters of the British Expeditionary Force in France and Flanders incorporated a GHQ Signals Company, two Corps Signals Companies (one each for I and II Corps), and specialist units for railways and printing. GHQ always maintained certain engineering units, including the Special Companies RE whose job was gas warfare, Meteorological, Special Works Park (camouflage) and other specialists.
As the army grew in size, the number of Corps increased and were organised into Armies. At Army level, several different types of Engineers units developed, and Corps were left with only one Company-sized unit, in motor and cable sections. Each of the five Armies on the Western Front contained the following, with the establishment varying between Armies and over time.
- Advanced RE Parks (responsible for stores and dumps of goods and equipment)
- Pontoon Parks (looking after bridging equipment)
- Electrical and Mechanical Companies (responsible for machinery, including underground boring)
- Army Workshops (for repairs and maintenance of equipment)
- Anti-Aircraft Sections (searchlight operations)
- Army Troops Companies (established similar to Field Companies, but for behind-the-lines bridging and water work)
- Tranportation Works Companies (maintaining vehicles)
- Forestry Companies
- Inland Waterways and Docks Companies
I hope to add some detail to this page in due course.