Final answer:
The Ottomans lost territory in Crimea between 1774 and 1830. This was during a period of decline due to military losses and rising European power. The 19th century saw further losses as nationalism led to independence movements.
Step-by-step explanation:
The Ottoman Empire began losing territory over a series of years due to various factors including military setbacks, governmental decentralization, and challenges from rising European powers and nationalist movements. The Crimea was lost by the Ottomans between 1774 and 1830. This corresponds to the period following the Ottoman's increasing military defeats and before the series of nationalist independence movements in the 19th century that saw Greece, Egypt, and Arabian territories gain their independence.
By the 1800s, the Ottoman Empire was in a significant decline, known as "the sick man of Europe," and faced continual territorial losses. During the 19th century, regions such as the Balkans and North Africa gradually slipped away from Ottoman control as European powers and rising nationalist sentiments diminished the once-mighty empire. The decline of the Ottoman Empire culminated with its eventual fall following World War I.