Taking Egypt would make the Ottoman Empire Britain's priority target

What follows if a more effective Ottoman campaign captures the Caucasus and Egypt in 1915?

The Ottomans may pressure Russia, but taking Egypt and Suez makes them Britain's foremost target and invites a very large imperial counterattack.

The scenario grants the Ottoman Empire enough military and logistical success to take Egypt and the Russian Caucasus in 1915. A loss of the Caucasus could put Russia under greater pressure, but Egypt would also become the focus of a British counteroffensive. The Nile and Suez Canal were important enough for Britain to redirect the Indian Army and other available forces. Japanese assistance is proposed as another possible source of troops. Ottoman gains would therefore create an urgent problem of holding territory against an enlarged coalition response. Persia would also have reason to be alarmed by the changed regional balance.