Osman I (c. 1258–1326) was the founder of the Ottoman Empire, which would grow from a small Anatolian beylik (principality) into a vast empire spanning three continents. He succeeded his father, Ertuğrul, as leader of the Kayı tribe of Oghuz Turks around 1281. Osman declared independence from the declining Seljuk Sultanate of Rum, and his name became the basis for the Ottoman dynasty and the empire itself (Osmanlı in Turkish). His followers were known as Osmanlıs (Ottomans). Which city did Osman I conquer in 1326, shortly before his death, making it the first major Ottoman capital?

The Conquest of Constantinople on May 29, 1453 was a pivotal moment in world history. Sultan Mehmed II (later known as "Mehmed the Conqueror"), then 21 years old, led the Ottoman army against the Byzantine capital after a 53-day siege. The Ottomans used massive cannons (including the giant "Basilica" cannon designed by Orban), transported ships overland on greased logs, and breached the legendary Theodosian Walls. The fall of Constantinople marked the end of the Byzantine (Eastern Roman) Empire and established Istanbul (as it became known) as the Ottoman capital. Which Byzantine emperor died defending Constantinople during the final assault?

Suleiman I (1494–1566), known as Suleiman the Magnificent in the West and Suleiman the Lawgiver (Kanuni) in the East, reigned as the tenth Ottoman sultan from 1520 to 1566 – the longest reign of any Ottoman sultan. Under his leadership, the Ottoman Empire reached its political, military, and cultural zenith. He conquered Belgrade (1521), Rhodes (1522), and most of Hungary (Battle of Mohács, 1526). He codified Ottoman law (Kanun), reformed the tax system, and was a patron of poets, architects (including Mimar Sinan), and artists. Suleiman led the unsuccessful Siege of which European city in 1529, marking the Ottomans' first attempt to capture the Habsburg capital?

The Janissaries (Yeniçeri, meaning "new soldier") were elite infantry units that formed the Ottoman sultan's household troops and bodyguards. The system, known as devşirme ("collection"), required Christian boys from the Balkans to be taken as a levy, converted to Islam, and trained for military or administrative service. Janissaries were renowned for their discipline, loyalty to the sultan, and mastery of firearms. They became a powerful political force and later a conservative obstacle to reform. The Janissary corps was established during the reign of which early Ottoman sultan?

The Battle of Lepanto (October 7, 1571) was a major naval engagement between the Ottoman Empire and the Holy League, a coalition of Catholic maritime states including Spain, Venice, Genoa, and the Papal States. The Holy League fleet, commanded by Don John of Austria, defeated the Ottoman fleet decisively in the Gulf of Patras (off western Greece). The Ottomans lost over 200 ships and approximately 30,000 men. While the Ottoman navy quickly rebuilt, Lepanto ended Ottoman naval supremacy in the Mediterranean. Which famous Spanish writer, who lost the use of his left hand in the battle, called it "the most memorable occasion that past centuries have ever seen"?

Mimar Sinan (c. 1488–1588) was the chief Ottoman architect and civil engineer for sultans Suleiman the Magnificent, Selim II, and Murad III. Over his 50-year career, he designed and supervised the construction of over 475 buildings, including mosques, palaces, bridges, aqueducts, and schools. His masterpiece is the Selimiye Mosque in Edirne, with its magnificent dome surpassing that of Hagia Sophia. Sinan developed the "octagonal buttressed dome" system that became a hallmark of Ottoman classical architecture. Sinan was originally conscripted through which Ottoman system?

The Second Siege of Vienna (July 14 – September 12, 1683) was a turning point in Ottoman-European relations. The Ottoman army, commanded by Grand Vizier Kara Mustafa Pasha, besieged the Habsburg capital with approximately 150,000 troops. The city was defended by a garrison of about 20,000. The siege was broken by the arrival of a Polish-German relief force under King John III Sobieski, who led the largest cavalry charge in history (about 18,000 horsemen, including the famous Winged Hussars). The Ottoman defeat marked the beginning of the Great Turkish War and Ottoman territorial decline. Which Polish king led the relief of Vienna?

The Millet system was the Ottoman administrative structure that granted non-Muslim religious communities autonomous authority over their personal status, family law, religious practice, and education. Each millet (meaning "nation" in Ottoman Turkish) was led by its religious head – the Greek Orthodox Patriarch, the Armenian Patriarch, and the Chief Rabbi – who collected taxes and represented the community to the sultan. This system allowed religious diversity to coexist under Islamic rule. The Millet system was formally established during the reign of which sultan following the conquest of Constantinople?

Selim I (1470–1520), known as Selim the Grim (Yavuz Sultan Selim), dramatically expanded the Ottoman Empire into the Middle East during his brief 8-year reign (1512-1520). He defeated the Safavid Persian Empire at the Battle of Chaldiran (1514), then conquered the Mamluk Sultanate of Egypt (1516-1517), gaining control of the Islamic holy cities of Mecca and Medina. After conquering Cairo, the Abbasid caliph formally transferred the title of Caliph (leader of the worldwide Muslim community) to Selim and his successors. Which battle ended Mamluk rule in Egypt?

The Ottoman Empire officially ended on November 1, 1922, when the Grand National Assembly of Turkey abolished the sultanate. The last Ottoman sultan, Mehmed VI, went into exile. The empire had sided with the Central Powers in World War I and suffered defeat. The Turkish War of Independence (1919-1923), led by Mustafa Kemal (later Atatürk), resulted in the abolition of the sultanate and the establishment of the Republic of Turkey on October 29, 1923. The Treaty of Lausanne (1923) recognized the new republic. Which World War I armistice forced the Ottomans to surrender and led to the Allied occupation of Constantinople?