By Laura Smith-Spark
BBC News, Washington
Military records featuring 90 million Americans who have fought in wars from the 1600s through the American Civil War to Korea and Vietnam have been brought together online.
Baseball star Babe Ruth registered for the draft for World War I and II
The huge collection of documents, which includes draft registration cards, photographs, prisoner of war records and news reels, is the work of family history website Ancestry.com.
It hopes to help millions of Americans uncover their ancestors' pasts through their military records, and to shed a little light on the nation's history as it marks Memorial Day on 28 May.
About a third of the records - some 30 million names - are now visible for the first time on the internet following the collection's launch on 24 May. Others were already searchable online.
The chances of finding a relative are reasonable - with every American male between the ages of 18 and 45 required to register for the draft during World War I, details were collected on some 24 million people. The site's World War II records feature a further 15 million names.
Ancestry has also digitally uploaded enlistment, prisoner of war and pension records from 1860 to 1865 featuring the names of some 18 million men who served in the Civil War.
Among the many names are some that are more familiar than others - today's rich, famous and notorious, or their ancestors.
Records show Tom Cruise's great-grandfather was short and stout
Diligent online celebrity hunters may come across the WWI draft registration card of Thomas Cruise Mapother, great-grandfather of actor Tom Cruise, who shares the same full name.
The description on his card - short, stout and bald - gives little clue that three generations down the line a Hollywood heart throb would be born.
Gangster Al Capone can also be found, listing "paper cutter" as his occupation on his WWI draft registration card, filed in 1918 in Brooklyn.
Baseball legend Babe Ruth registered for the draft in both World War I and World War II, by which time he was 47, giving "baseball player" as his occupation.
One of America's most famous magicians also registered for the draft in 1918, filling out his full name on the card as Harry Handcuff Houdini.
Hero or deserter?
Going further back in history, records reveal that Elvis Presley's great-great-grandfather, Dunnan Presley Jr deserted from the Confederate Army not just once but twice - having picked up a $300 enlistment payment each time.
Elvis's great-great-grandfather deserted from the army - twice
Megan Smolenyak, chief family historian for Ancestry, says it is often military history that first sparks an interest in genealogy in men.
"They find some ancestor served in the American Civil War and start looking for the rest of their roots as well. There's always the chance that you are going to end up with a really good story of heroics.
"One of your best shots for bringing your records to life can be the pension files, with medical and physical descriptions. It can be quite juicy sometimes."
Of course, not everyone is a hero and some people may discover their ancestors had a poor disciplinary record or went AWOL.
"Fortunately most people, whatever the truth is, aren't too upset if they find something like that. It's just a colourful story to tell rather than something to hide," says Ms Smolenyak.
In some cases, records reveal long family histories of military service.
Wartime images, photographs and news reels can be seen online
Presidential hopeful and Arizona Senator John McCain's record as a navy pilot during the Vietnam War, during which he was shot down over Hanoi and spent five years as a prisoner of war, is well known.
Fewer people may know that he is the third of three generations of John S McCains to have graduated from Annapolis Naval Academy in Maryland. His father was Commander-in-Chief of the US Pacific Command during Vietnam and his grandfather was an admiral during WWII.
James Stewart, who was one of the first movie stars to enlist for WWII service, had a great-great-great grandfather who fought in the Revolutionary War and a grandfather who served in the Union Army during the Civil War. His adopted son, Ronald McLean, died in action in Vietnam.
His records show he was 6'2" (1.87m) tall and weighed only 145lb (66kg), Ms Smolenyak says - one of many cases which show how much larger people have become on average, particularly in the US.
Other documents, including letters and photographs, give clues to what women were doing in war time, particularly during World War II.
Harry Houdini's military records show his middle name as Handcuff
The records people find for their own relatives can be built into an online family tree that other family members can access using the site.
For two weeks, from 24 May to 4 June, the military collection will available for anyone to access free of charge. Census and other records from other countries are also available online.
"What a lot of people react to is seeing their ancestor's signature for the first time, seeing their handwriting, or sometimes just an 'X' if they weren't literate yet," says Ms Smolenyak.
"It's one of the most simple things but they really feel they are getting in touch with their ancestors when they see a piece of paper they have actually handled."