South Arabia during World War I
The campaign in South Arabia during World War I was a minor military campaign for control of the port city of Aden, an important way station for ships on their way from Asia to the Suez Canal. The British Empire declared war on the Ottoman Empire on 5 November 1914, and the Ottomans responded with their own declaration on 11 November.
Source: Wikipedia — South Arabia during World War I (CC BY-SA 4.0)