The 53rd (Welsh) Division before and at the outset of the First World War was the original Welsh territorial division and was at camp on August 4th 1914 the day Great Britain declared war on Germany (and the lamps went out allover Europe). A general order for mobilization was issued on August 5th. The next few months saw various battalions leave and join the Division so that eventually one of the Brigades (160th) had lost its Welsh flavour, comprising as it did of Home Counties battalions. The 158 and 159th however retained their Welsh and Borders character.
Much of the Divisions pre-deployment training took place in the East of England with the 4th and 5th Battalions, the Welsh Regiment based at Bedford. On 3rd July 1915 the Divisional Commander was ordered to prepare the 53rd for service in the Mediterranean. Embarkation was complete by July 19th and a fleet of eight transport ships sailed.

Reference: “History of the 53rd (Welsh) Division (T.F.) 1914-1918”. Major CH Dudley Ward DSO, MC. The Naval and Military Press. 1927