6 of the Deadliest Wars in American History: A DIY Genealogy Guide
If you’re researching American family history, there’s a strong chance that at least one of your ancestors served in a major conflict. The six deadliest wars in American history claimed over 1.3 million American lives and affected virtually every family in the country, meaning most records of the time reference them in some way. Each conflict created mountains of paperwork, and that’s great news for anyone tracing their family tree, because if you know which war your ancestor fought in, it tells you exactly which records you should be checking. In this article, we take a look at six of the biggest wars in American history, showing the types of records they led to and what they can do for your family tree.
Key facts on wars in American history:
- Over 620,000 Americans died in the Civil War (1861–1865), making it the deadliest war ever fought in the United States
- WWII created the most thorough service documentation, with nearly everyone who served having a detailed file
- Revolutionary War pension applications pack in biographical details you won’t find anywhere else, even if the basic service records are thin
- Vietnam War files only became fully accessible to researchers recently, so there’s a lot of new material to work with
- You’ll often learn things about your ancestors from military records that never made it into any other documents
The 6 deadliest wars in American history
When tracking down military ancestors, knowing which war they fought in tells you which records to look for. The casualty numbers shown below are extremely high, illustrating why nearly every American will have a family member who was involved in at least one of these conflicts.
1. The American Revolutionary War (1775–1783)
The battle for American independence in the late 1700s took approximately 25,000 lives. Pension applications filed decades after the Revolutionary War can be a real treasure trove, as veterans would provide detailed life stories. Widows would document marriages and children, too, which can all be searched through MyHeritage’s military collections.
2. The American Civil War (1861–1865)
This major civil war killed over 620,000 people, making it America’s deadliest war. Service records track soldiers from enlistment to discharge, and pension files cover veterans, widows, and orphans. Wounded ancestors also often have surgeons’ certificates describing injuries from both the Confederate and Yankee sides.
3. World War I (1917–1918)
While America only joined World War I in 1917 and was actively engaged for just 19 months, it still cost 116,500 U.S. lives. Draft cards give you physical descriptions and addresses for every man aged 18–45, whether they served or not.
4. World War II (1941–1945)
Another global war claimed 405,000 American lives. For researchers, World War II is also notable for the breadth and detail of surviving U.S. military records. Service files document everything, and unit reports pinpoint where your ancestor was on specific dates.
5. The Korean War (1950–1953)
Coming just five years after peace broke out in Europe, this conflict in the Far East killed 36,500 Americans. You’ll find service files and casualty reports, though some records remain restricted.
6. The Vietnam War (1955–1975)
Many were against troops being sent to Vietnam in a bid to stop the spread of communism, but that didn’t stop 58,000 Americans from being killed. Records for this war only opened up recently, creating new research opportunities through MyHeritage’s newspaper archives and databases.
The more recent conflicts have incredibly detailed individual files. If you’re not sure where your ancestor served, start with MyHeritage’s military record search. You can search across all conflicts at once and see what comes up.
What do these records reveal beyond the service?
Military records do far more than just confirm someone served. They capture details that census records, birth certificates, and marriage licenses never touch. A pension application might explain why your ancestor walked with a cane in that 1920s photograph, such as if he took shrapnel to the leg.
A draft card might show that your ancestor worked as a coal miner in Pennsylvania — something you might not find anywhere else. Widow’s pension files often also include sworn statements from neighbors about how long a couple was married, where they lived, and who knew your forebears.
There’s a whole raft of documentation created during wartime, and as we can see, they can present a very rounded picture of a person back in the day.
| Record type | What you can discover |
|---|---|
| Pension applications | Physical descriptions, childhood injuries, scars, and disabilities that explain old photographs. Veterans had to prove their service with detailed life stories. |
| Draft cards | Occupations, physical descriptions, addresses, and employment details for every man aged 18–45 — even those who never served. |
| Widow’s pensions | Neighbor testimonies offer insight from people who knew them. They can open up entire communities accessible through census records. |
| Service records | Enlistment dates, promotions, transfers, wounds, and sometimes reasons for desertion — dying wives, farms being seized, family emergencies. |
| Morning reports | Daily unit activities capturing small personal moments, including packages from home, promotions, trips to the infirmary, and letters received. |
| Surgeon’s certificates | Detailed injury descriptions, physical examinations, and medical conditions that affected veterans for life. |
While searching these records, you may also stumble across family connections you didn’t know about, like brothers who enlisted together, cousins in the same unit, and fathers and sons who fought in different wars.
Discover your family’s military history today
Between the Revolutionary War and Vietnam, these six conflicts touched almost every American family. Beyond confirming service, the paperwork left behind shows you what your ancestors did for a living, what injuries they suffered, who they served alongside, and what military life was actually like.
At MyHeritage, you can search military records from all six wars in one place. We’ve got pension applications, draft cards, service files, and casualty reports. Your ancestor might’ve fought at Yorktown or in the jungles of Vietnam. Either way, the best place to find those records is here.
Ready to dig in? Start searching today and find out what your family was doing during the moments that shaped America.
FAQs about American war casualties and family history
Which war has the most accessible records for genealogists?
World War II, hands down. The documentation is incredibly thorough, and most records are publicly available. WWII service files include everything from basic training through discharge, making it the easiest conflict to research.
My ancestor died in the Civil War. What records should I look for?
Go for the compiled military service records first — they’ll tell you which unit he was in and when he died. After that, check pension files. His widow or parents probably filed for benefits. If he died in combat, local newspapers from his hometown often ran casualty lists.
Are Revolutionary War records hard to find?
The basic service records can be pretty thin, but the pension applications? Those are packed with information. Veterans filed these decades after the war ended, so they had to include all sorts of biographical details you won’t find anywhere else.
Can I find records if my ancestor didn’t actually serve?
Absolutely, especially for WWI and WWII. Just about every man of draft age had to register, whether he ended up serving or not. Those registration cards have birth dates, jobs, physical descriptions — all kinds of useful genealogy information.
Why are some Korean War records still restricted?
There’s a 62-year privacy rule on certain personnel files after someone leaves the service. Some Korean War records still fall under that, though plenty are available now. Vietnam records had the same issue, but most of those have opened up.
Gavin Crawley is a freelance writer with over 15 years of experience and a strong personal passion for genealogy. He combines his professional writing skills with a deep curiosity about family history, helping others explore their roots through clear, engaging content. Gavin draws on his own research experience to make complex topics more accessible to readers at all stages of their genealogical journey.
