The United States military entered the Korean War in July 1950 and fought on the side of South Korea against the communist forces of North Korea and the People's Republic of China until August 1953. In total, the United States military would suffer almost 37,000 deaths through hostilities. Of these, servicemembers in the Army made up the vast majority of deaths (82.19 percent), with most of these being the result of soldiers being killed in action. A smaller number of marines and navy servicemembers were killed in Korea, with the majority also having been killed in action for these groups. For the United States Air Force, the composition of total deaths is quite different, as the majority of pilots killed during the conflict were declared dead after going missing in action. This likely reflects the fact that when an airplane was shot from the sky in battle, the remains of the pilots are not recoverable.

The American Civil War is the conflict with the largest number of American military fatalities in history. In fact, the Civil War's death toll is comparable to all other major wars combined, the deadliest of which were the World Wars, which have a combined death toll of more than 520,000 American fatalities. The ongoing series of conflicts and interventions in the Middle East and North Africa, collectively referred to as the War on Terror in the west, has a combined death toll of more than 7,000 for the U.S. military since 2001. Other records In terms of the number of deaths per day, the American Civil War is still at the top, with an average of 425 deaths per day, while the First and Second World Wars have averages of roughly 100 and 200 fatalities per day respectively. Technically, the costliest battle in U.S. military history was the Battle of Elsenborn Ridge, which was a part of the Battle of the Bulge in the Second World War, and saw upwards of 5,000 deaths over 10 days. However, the Battle of Gettysburg had more military fatalities of American soldiers, with almost 3,200 Union deaths and over 3,900 Confederate deaths, giving a combined total of more than 7,000. The Battle of Antietam is viewed as the bloodiest day in American military history, with over 3,600 combined fatalities and almost 23,000 total casualties on September 17, 1862. Revised Civil War figures For more than a century, the total death toll of the American Civil War was generally accepted to be around 620,000, a number which was first proposed by Union historians William F. Fox and Thomas L. Livermore in 1888. This number was calculated by using enlistment figures, battle reports, and census data, however many prominent historians since then have thought the number should be higher. In 2011, historian J. David Hacker conducted further investigations and claimed that the number was closer to 750,000 (and possibly as high as 850,000). While many Civil War historians agree that this is possible, and even likely, obtaining consistently accurate figures has proven to be impossible until now; both sides were poor at keeping detailed records throughout the war, and much of the Confederacy's records were lost by the war's end. Many Confederate widows also did not register their husbands death with the authorities, as they would have then been ineligible for benefits.

In 2023, the mortality rate across all branches of the armed forces of the United Kingdom was 50 deaths per 100,000 personnel. The mortality rate was highest among members of the Royal Navy / Marines at 62 deaths per 100,000 personnel, and lowest among those in the RAF at 50.

In 2023 there was one operational death in the British Armed Forces, the same number as in 2022 and 2021. Since 1945, the deadliest year for British Armed forces was 1951, when there were 851 operational deaths. This was due to three separate conflicts: the Malayan Emergency, the 1951 Anglo-Egyptian War and the Korean War. Between 1959 and 2009 there were only three years that had more than 100 operational deaths: 1972, 1973 and 1982. The spike in deaths in the early 1970s were the result of the political violence in Northern Ireland at the time, and 237 of the 297 deaths in 1982 happened during the Falklands War. Over this period, there have been a total of 7,193 British military deaths in conflicts. Size of armed forces at a historic low in 2023 The British Armed Forces are composed of four separate branches, the British Army, the Royal Navy, the Royal Air Force and the Royal Marines. Of these branches, the British Army has more personnel than the other three combined at 77,540. The Royal Air Force had 32,180 personnel, the Navy 26,330, and the Marines 6,510 amounting to 142,560 active personnel. This was the fewest number of personnel in modern times, and is partly explained by modernization efforts, which sought to de-emphasize the importance of a large army based on manpower in favor of a more advanced one based on technology. Long-term defense cuts   These cutbacks in personnel are also a result of the UK government spending far less on defense than it used to. In 1984, for example the UK spent around 5.5 percent of GDP on defense, compared with just 2.3 percent in 2021. The end of the Cold War in the early 1990s made it difficult to justify 1980s-levels of military spending during this time period, along with the UK having far fewer overseas commitments than in the past. Russia's full-scale invasion of Ukraine in 2022, however, may reverse this trend, with many NATO allies pledging to increase their defense budgets in light of the new geopolitical situation. This particular issue will become even more pertinent if Donald Trump, a known skeptic of NATO, is elected as U.S. President in November 2024.

In the fiscal year of 2019, 21.39 percent of active-duty enlisted women were of Hispanic origin. The total number of active duty military personnel in 2019 amounted to 1.3 million people.

Ethnicities in the United States The United States is known around the world for the diversity of its population. The Census recognizes six different racial and ethnic categories: White American, Native American and Alaska Native, Asian American, Black or African American, Native Hawaiian and Other Pacific Islander. People of Hispanic or Latino origin are classified as a racially diverse ethnicity.

The largest part of the population, about 61.3 percent, is composed of White Americans. The largest minority in the country are Hispanics with a share of 17.8 percent of the population, followed by Black or African Americans with 13.3 percent. Life in the U.S. and ethnicity However, life in the United States seems to be rather different depending on the race or ethnicity that you belong to. For instance: In 2019, native Hawaiians and other Pacific Islanders had the highest birth rate of 58 per 1,000 women, while the birth rae of white alone, non Hispanic women was 49 children per 1,000 women.

The Black population living in the United States has the highest poverty rate with of all Census races and ethnicities in the United States. About 19.5 percent of the Black population was living with an income lower than the 2020 poverty threshold. The Asian population has the smallest poverty rate in the United States, with about 8.1 percent living in poverty.

The median annual family income in the United States in 2020 earned by Black families was about 57,476 U.S. dollars, while the average family income earned by the Asian population was about 109,448 U.S. dollars. This is more than 25,000 U.S. dollars higher than the U.S. average family income, which was 84,008 U.S. dollars.

In 2024, the average age for personnel in the UK Armed Forces overall was 31 years old. The average age of those serving in the British Army was also 31, with the average age rising to 32 for the Royal Navy and Marines, and was 33 for the Royal Air Force (RAF). The average age for officers in the Armed Forces was 37, with this rising to 38 for officers in the Royal Air Force. Personnel falls to historical lows in 2024 Overall, there has been a long-term decline in the size of the armed forces, with the number of personnel declining from over 200,000 in 2000, to around 138,120 by 2024. In fact, the size of the armed forces has been in almost constant decline since the end of World War Two. Britain's retreat from its colonial empire throughout this period removed many of the UK's overseas commitments, with the end of the Cold War also leading to further cuts to personnel. Operational deaths since the Second World War Since 1945 there have been 7,193 operational deaths in the United Kingdom’s armed forces, with the deadliest year occurring in 1951 when there were 851 deaths. This was due to three separate conflicts: the Malayan Emergency, the 1951 Anglo-Egyptian War and the Korean War. Since 1959, there were only three years that had more than 100 operational deaths: 1972, 1973 and 1982. By comparison, between 2016 and 2024, there have been only nine operational deaths, with just one death reported throughout the whole of 2023.