Battle of Mecca took place in Mecca, in what is now known today as Saudi Arabia, following the fall of Ta'if to King Abdulaziz Ibn Saud in his campaign to conquer the Kingdom of Hejaz.
 King Hussein bin Ali fled from Mecca to Jeddah, leaving behind a cache of weapons in the Qishla of Mecca which were recovered by Saudi forces.
 The battle in Mecca resulted in Hashemite defeat to Saudis and the allied Ikhwan.
The McMahon–Hussein Correspondence, or the Hussein–McMahon Correspondence, was a series of ten letters exchanged from July 1915 to March 1916, during World War I, between Hussein bin Ali, Sharif of Mecca, and Lieutenant Colonel Sir Henry McMahon, British High Commissioner to Egypt, concerning the political status of lands under the Ottoman Empire.
 In the letters Britain agreed to recognize Arab independence after World War I "in the limits and boundaries proposed by the Sherif of Mecca", with the exception of "portions of Syria" lying to the west of "the districts of Damascus, Homs, Hama and Aleppo", in exchange for launching the Arab Revolt against the Ottomans as a "quid pro quo".
The Battle of Mecca occurred in the Muslim holy city of Mecca in June and July 1916.
 On June 10, the Sharif of Mecca, Hussein bin Ali, the leader of the Banu Hashim clan, started a revolt against the Ottoman Caliphate from this city.
 The Battle of Mecca was part of the Arab Revolt of World War I.
Faisal I bin Hussein bin Ali al-Hashemi, (Arabic: فيصل بن الحسين بن علي الهاشمي‎ ‎ , "Fayṣal al-Awwal ibn al-Ḥusayn ibn ‘Alī al-Hāshimī"; 20 May 1885 – 8 September 1933) was King of the Arab Kingdom of Syria or Greater Syria in 1920, and was King of Iraq from 23 August 1921 to 1933.
 He was the third son of Hussein bin Ali, the Grand Sharif of Mecca, who had proclaimed himself King of the Arab lands in October 1916.
The Battle of Taif was fought between Ottoman forces and Syed Hussien bin Ali Sharif of Mecca in 1916.
 The Ottoman Army was in Taif, with Syed's forces besieging the city and after many weeks siege and fiercest struggle Syed's forces were able to capture the Taif.
 After the fall of Mecca in July 1916 the fall of Taif was a major blow for Turks who were fighting in First World War against Britain.
 The British helped Syed Hussien's bin Ali's Forces by providing them with guns.
The Arab Revolt started by Sherif Hussein ibn Ali had a series of campaigns, starting from Mecca in June 1916.
 Here is a list of these campaigns:
Medina, an Islamic holy city in Arabia, underwent a long siege during World War I.
 Medina was at the time part of the Ottoman Empire.
 In the war, the Ottoman Empire sided with the Central Powers.
 Sharif Hussain of Mecca revolted against the caliph and the Ottoman Empire which, under the leadership of the nationalistic Young Turks, had ignored the wishes of the Caliph and sided with the Central Powers.
 Hussain instead sided with the British Empire.
 T. E. Lawrence was instrumental in this revolt.
 Hussain occupied Mecca and besieged Medina.
 It was one of the longest sieges in history that lasted till even after the end of war.
 Fahreddin Pasha was the defender of Medina.
 Some celebrated him as ""the Lion of the Desert"" despite the suffering of those who remained in Medina.
 The siege lasted two years and seven months.
Abdullah I bin al-Hussein, King of Jordan (Arabic: عبد الله الأول بن الحسين‎ ‎ , "Abd Allāh ibn al-Husayn", February 1882 – 20 July 1951), born in Mecca, Hejaz, Ottoman Empire, was the second of three sons of Hussein bin Ali, Sharif and Emir of Mecca and his first wife Abdiyya bint Abdullah (d. 1886).
 According to Abdullah, he was a 38th-generation direct descendant of Muhammad as he belongs to the Hashemite family.
Ali bin Hussein, GBE (Arabic: علي بن الحسين بن علي الهاشمي‎ ‎ , "‘Alī ibn al-Ḥusayn ibn ‘Alī al-Hāshimī"; 18791935) was King of Hejaz and Grand Sharif of Mecca from October 1924 until he was deposed by Ibn Saud in December 1925.
 He was the eldest son of Sharif Hussein bin Ali, the first modern King of Hejaz, and a scion of the Hashemite family.
 With the passing of the kingship from his father he also became the heir to the title of Caliph, but he did not adopt the khalifal office and style.
The Arab Revolt (Arabic: الثورة العربية‎ ‎ , "al-Thawra al-‘Arabiyya "; Turkish: "Arap İsyanı" ) or Great Arab Revolt (Arabic: الثورة العربية الكبرى‎ ‎ , "al-Thawra al-‘Arabiyya al-Kubrā ") was officially initiated by Sherif Hussein bin Ali at Mecca on 10 June 1916 (9 Sha'ban of the Islamic calendar for that year) although his sons ‘Ali and Faisal had already initiated operations at Medina starting on 5 June with the aim of securing independence from the ruling Ottoman Turks and creating a single unified Arab state spanning from Aleppo in Syria to Aden in Yemen.

Question: What was officially initiated by Sherif Hussein bin Ali at Mecca on 10 June 1916, and was part of the Siege of Medina that occurred during World War I?
Answer: Arab Revolt