Here's a quick list that I'm posting here in preparation for deployment to the wiki. All wars and total casualties:
Sicilian War for Independence: 1901-1902
Total Casualties: 45,200
Colombian Civil War: 1902-1904
Total Casualties: 228,000
Bulgarian War for Independence: 1904-1910
Total Casualties: 699,000
The Great War: 1904-1908
Total Casualties: 18,393,000
Italian Wars of Unification: 1904-1909
Total Casualties: 2,804,200
Chaldean-Kurd War: 1908
Total Casualties: 159,000
Opsikion's War for Anatolia: 1908-1910
Total Casualties: 597,700
Pontic-Turkish War: 1909-1910
Total Casualties: 99,000
Second Hungarian Civil War: 1910-1914
Total Casualties: 1,362,100
Aztec War for Independence: 1910-1913
Total Casualties: 672,000
Afghan War for Independence: 1910
Total Casualties: 39,000
Romanian Uprising: 1911
Total Casualties: 75,000
New Spanish War of Separation: 1912-1913
Total Casualties: 96,000
The American Crisis: 1912-1918
Total Casualties: 3,640,000
Second Spanish Civil War: 1916-1918
Total Casualties: 2,252,000
Serbian Intervention: 1916
Total Casualties: 159,000
Ecuadorian Proletarist War: 1916-1917
Total Casualties: 297,300
Turk-Kurdish War: 1916-1919
Total Casualties: 240,200
Hollandian War of Independence: 1917-1919
Total Casualties: 111,000
Great Arabian War: 1919-1922
Total Casualties: 2,835,900
Mayan Civil War: 1920-1921
Total Casualties: 195,000
Invasion of Azerbaijan: 1920
Total Casualties: 519,000
Rhine-Rhone War: 1922-1926
Total Casualties: 6,628,600
Portuguese Invasion of Jamaica: 1923
Total Casualties: 63,000
Reclamation of Chaldea War: 1923
Total Casualties: 273,000
The Pacific War: 1923-1925
Total Casualties: 643,700
Danish Civil War: 1924
Total Casualties: 151,800
The East African Wars: 1924-1928
Total Casualties: 1,113,700
Catalonian War for Independence: 1925
Total Casualties: 27,000
Brazilian Assault on Jamaica: 1926
Total Casualties: 93,400
Angolan Revolution: 1926-1927
Total Casualties: 105,000
Cuban Civil War: 1928-1929
Total Casualties: 112,500
Southeast African War of Independence: 1928-1930
Total Casualties: 270,000
The Tunisian War: 1930-1932
Total Casualties: 573,400
Burundi-Zambian War: 1930-1931
Total Casualties: 93,000
The Fireworks War: 1930-Present
Total Casualties to Date: 11,117,400
War of the Colorado River: 1931-1933
Total Casualties: 441,400
Holy Land Rebellion: 1931-1932
Total Casualties: 183,100
De Luz's War: 1932-1935
Total Casualties: 153,100
Kabinde War of Independence: 1932
Total Casualties: 27,000
The Reclamation War: 1933-Present
Total Casualties to Date: 4,718,100
Gabon's War for Independence: 1933
Total Casualties: 30,000
Chad's War for Independence: 1933
Total Casualties: 39,100
Mali's War for Independence: 1933-1934
Total Casualties: 225,200
War of the False Emperor: 1934-1935
Total Casualties: 342,800
Chokwe-Ovambo War: 1934-1935
Total Casualties: 93,000
Benin's War for Independence: 1934
Total Casualties: 124,300
Indian Civil War: 1934-Present
Total Casualties to Date: 1,731,900
Angolan Civil War: 1935-1936
Total Casualties: 39,100
Korean Rebellion: 1935-Present
Total Casualties to Date: 891,000
Chokwe Invasion of Burundi: 1936
Total Casualties: 54,000
Uruguayan Civil War: 1937-Present
Total Casualties to Date: 21,100