Again, it goes down to them being used to a different style of warfare. The First World War was the dawn of the modern era of warfare, with the introduction of things like tanks and military aircraft. You only have to look how the Ottomans would mess up to see my point about all sides finding it difficult to adapt.

For example, the first confrontation between Britain and Germany was a cavalry charge between two mounted divisions. In fact, and I can't remember the actual battle, but during the end of the war, the British led the last ever successful cavalry charge, against the Ottomans. The fact they still fought with horses, sabres, lances, and cavalry charges shows just how mixed the fighting styles of the war was.

Also remember that the British in those regions were often ill equipped and relied on colonial militia to bolster their numbers, and unfortunately these militia forces were not as well trained and would flee or turn traitor.