The Italo-Turkish War (1911-1912), now remembered primarily as Italy’s war for what is now Libya, swelled from a localized colonial invasion into a significant Mediterranean conflict and a global cause célèbre that attracted aid for the embattled Ottoman regime from diverse locations. This paper investigates the vital contribution of Pan-Islamism (or ?ttihad-? ?slâm in Ottoman Turkish) to the Ottoman efforts to defend its last foothold in Africa from Italian aggression. While many studies tend to brush aside the importance of early twentieth-century Pan-Islamism as either a pipe dream of Wilhelmine champions of German imperialism and their Ottoman collaborators or a mere rhetorical movement devoid of substantial consequence, my research reveals how global appeals to Islamic unity to combat European expansionism translated into material benefits for Ottomans on the battlefield and bolstered Pan-Islamic politics in Istanbul. Through an examination of documents from the Turkish Red Crescent and the Turkish General Staff archives, I highlight the crucial assistance of global Islamic humanitarian aid to the Ottoman war effort in the form of sizeable financial contributions to the Ottoman Red Crescent and the British Red Crescent from Muslims over the duration of the conflict. The Red Crescent organization provided a means to funnel aid to the battlefield collected in mosques and Islamic associations within and without the Ottoman Empire. Ultimately, this charitable aid facilitated the deployment to North Africa of one British Red Crescent and three Ottoman Red Crescent teams which assumed in most cases sole responsibility for the medical care of both soldiers and civilians of the Ottoman province. Simultaneously, the Ottoman ranks ballooned as calls for coreligionist volunteers to take up arms in Libya were heeded throughout Africa and Asia. Ultimately, Muslims around the world shouldered a great deal of the cost of the conflict. While Italy’s coffers nearly ran dry fighting their war for colonial expansion, the defense of Libya cost the Ottoman treasury very little. This Islamic material support strengthened the position of Pan-Islamists in Istanbul and within the CUP (Committee of Union and Progress) contributing to an Islamic turn in imperial politics and a move away from the secular and inclusive Ottomanist discourse of the early years of the Second Constitutional Period. It further set a precedent for effective resistance to European imperialism that politicians and soldiers of the Ottoman lands later employed in the decade of war that followed.