Examine the rise of the Ottoman Empire. Who were the important leaders in this process? What role did the sense of Holy War play in this expansion?
The Ottoman Empire is also known as the Turkish Empire (in Turkey). The rulers involved in its founding as a Sunni Islamic state were Osman I from Anatolia which was in the late 13th century. It was Osman I who sent the Oghuz Turks to take possession. Then there were battles taking over the Balkan Islands by Murad in the late 14th century and, finally, the overtaking of what would become the capital of the Ottoman Empire: Constantinople. This was done by Mehmed II in the mid fifteenth century. Previously to the conquest of Constantinople, the Ottoman Empire was considered a "sultanate" (ruled by a sultan) but now was considered a true "empire" ruled by an emperor.
Even though your question asked about the rulers above (and specifically the ones that led to the "rise" of this empire, I would be amiss if I didn't mention the ruler at its height: Suleiman the Magnificent. During this point (during the 1500s and 1600s), the Ottoman Empire had great power. Quite literally, it connected the East and the West by controlling much of Europe, Western Asia, Caucasus, and Africa.
In regards to your question about "Holy War," I couldn't help but smile because it is precisely the Ottoman Empire that PREVENTED the crusades from being victorious! This can be seen specifically in the Battle of Nicopolis in the late fourteenth century.
The Battle of Nicopolis in 1396, widely regarded as the last large-scale crusade of the Middle Ages, failed to stop the advance of the victorious Ottoman Turks.
The Christians of the Europe of the Middle ages LOST because they couldn't stop the Ottoman Turks from advancing. In this way, much to most of Europe's chagrin, the crusades were a failure. Or, I guess we could say, that the Turks WON the holy war!