The Shiite resistance against the British occupation of Iraq is an important event and a turning point in the modern history of Iraq. In order to understand it, there is a need for a thorough examination of the short-term changes that happened during this period. Thus, the aim of this thesis is to examine the role that the Shiite community played in resisting the British occupation of Iraq during the period 1914-1921. It also considers their contribution to the formation of the modern State of Iraq under the rule of Faisal b. Al-Sharīf Ḥussein. Further, it analyses the role of this resistance in the emergence of the signs of nation building. The hypothesis that this study is testing is the role that the supreme cleric in Najaf, as an individual or belonging to an organization, and his fatwa in 1914 played in supporting the Ottoman Empire. In addition, the study involves the examinations of complex factors and overlapping elements such as those reflected in the relationships between the major powers (Ottoman and British forces) and regional rulers as well as entities and individuals such as; Khaʻzal in Al-Muhammarah, Ibn Sa‘ūd in the Arabian peninsula, Mubārak Al-Ṣabāḥ in Kuwait, the tribes in the south of Iraq and the coalitions of tribes, the jihadi movements during the First World War in the south and middle of Iraq, the national movement and political parties in Baghdad. This thesis is limited to studying the role of Shiites in the resistance of the British occupation of Iraq, and in the formation of modern Iraq in the period between 1914-1921. Limiting the exploration to this period and to the role of only the Shiites, which constituted about fifty-two percent of the Iraqi population in the period of the study, afforded the research a degree of specificity that allowed an in-depth exploration of a topic that has, hitherto, received little attention. Despite a fairly extensive and diverse literature that the study depended on, most of these sources lack analytical depth about the institutional and intellectual construction of al-Marja‘iyya (the Shiite religious authority). In particular, the latter is known to be limited to the religious and social aspects in the life of the followers, while it issued a fatwa on jihad addressed Muslims in general and non-Muslims living within the borders of the three vilayets to defend the land. To enable the researcher and readers to garner a thorough understanding of all these complicated relationships makes it imperative to use a suitable approach. Therefore, the continuity and change concept is used to understand the Shiite resistance against the British. In addition, this thesis uses the transnational history approach. This approach allows for exploring the circulation process of the fatwa(s) from its original place of issuance to other areas in Iraq. It also helps identify how the spiritual thoughts moved and were dispatched to other areas in different provinces. Although the period the study addresses may seem very short, it witnessed many changes that affected Iraq and the aforementioned major countries. By the outbreak of the First World War, Iraq had become an arena for warring forces and was involved in the war. The arrival of British troops in the Faw region on 6 November 1914 and their occupation of Basra in November 1914 began a causal chain of events and change, which affected Iraqi society. These events also led to the penetration of religious thought in the Iraqi society through fatwas issued by Shiite clerics in various parts of the country.