April thumb|June 9: The Final Act of the Congress of Vienna is signed. thumb|Twelfth Night. Caricature of the Congress of Vienna by George Cruikshank. April 10– Mount Tambora in the Dutch East Indies blows its top explosively during its peak eruption, killing more than 92,000 people during week of activity from April 5 to April 12. The blast propels thousands of tons of aerosols (Sulfide gas compounds) into the stratosphere, and the high level gases reflect sunlight, causing widespread cooling from a volcanic winter. During 1816, heavy rains fall arounde the world, snow falls in June and July in the Northern Hemisphere, crops fail and widespread famine occurs. In later years, 1816 will become known as the Year Without a Summer. April 21 – In India, the eastern part of the former Garhwal Kingdom is joined with Kumaon division, under the administration of the British Raj. April 24 – The Second Serbian Uprising against Ottoman rule takes place in Takovo, Ottoman Serbia. By the end of the year Serbia is acknowledged as a semi-independent state, temporarily achieving the ideals of the First Serbian Uprising.
April thumb|June 9: The Final Act of the Congress of Vienna is signed. thumb|Twelfth Night. Caricature of the Congress of Vienna by George Cruikshank. April 10– Mount Tambora in the Dutch East Indies blows its top explosively during its peak eruption, killing more than 92,000 people during week of activity from April 5 to April 12. The blast propels thousands of tons of aerosols (Sulfide gas compounds) into the stratosphere, and the high level gases reflect sunlight, causing widespread cooling from a volcanic winter. During 1816, heavy rains fall arounde the world, snow falls in June and July in the Northern Hemisphere, crops fail and widespread famine occurs. In later years, 1816 will become known as the Year Without a Summer. April 21 – In India, the eastern part of the former Garhwal Kingdom is joined with Kumaon division, under the administration of the British Raj. April 24 – The Second Serbian Uprising against Ottoman rule takes place in Takovo, Ottoman Serbia. By the end of the year Serbia is acknowledged as a semi-independent state, temporarily achieving the ideals of the First Serbian Uprising.