World War I casualties
The total number of military and civilian casualties in World War I were about 40 million: estimates range from 15 to 19 million deaths and about 23 million wounded military personnel, ranking it among the deadliest conflicts in human history.
Demographics of Croatia
In addition to demographic losses through significant migrations, the population of Croatia suffered significant losses due to wars and epidemics. In the 20th century alone, there were several such events. The first was World War I, when the loss of the population of Croatia amounted to an estimated 190,000 persons, or about 5.5% of the total population recorded by the 1910 census. The 1918 flu pandemic started to take its toll in Croatia in July 1918, with peaks of the disease occurring in October and November. Available data is scarce, but it is estimated that the pandemic caused at least 15,000–20,000 deaths. During World War II, nearly 195,000 people died in the territory of present-day Croatia. The surrender of the armed forces of the Independent State of Croatia and of the civilians accompanying the troops of the British Army at the end of World War II was followed by repatriation and subsequent events that became known as the Bleiburg tragedy. A substantial number of people were executed, but the exact number is disputed. The claims range from 12,000–15,000 to as many as 80,000 killed in May 1945. Finally, approximately 20,000 were killed or went missing during the 1991–1995 Croatian War of Independence. The figure pertains only to those persons who would have been recorded by the 1991 census as living in Croatia.