The Arab Revolt commences: June 5, 1916

The Arab Revolt against the Ottoman Empire commences, lead by the Hashemites of Mecca.

Movements towards greater Arab autonomy within the  Ottoman Empire had been going on for some time prior to the revolt.  Perhaps not surprisingly, they had been centered in the Lavant, i.e., Syria, which was a much more cosmopolitan and urban region of Arabia than the Arabian Peninsula.  Given the slow movement of the Ottoman Empire in this direction, indeed, given the slow disintegration of the Ottoman Empire, it's unlikely that a revolt would have broken out in 1916, let alone that it would have been centered in the Hajez, but for the outbreak of World War One which stressed the "sick man of Europe" and which gave rise to opportunities to potential Arabian rulers.  The British presence in Egypt (technically part of the Ottoman Empire), the raging war in Europe, the commitment to the Ottoman Empire to the Central Powers in November 1914, all gave rise to a situation which brought about the halting revolution against the Ottomans in 1916.