The battle of Adrianople was one of Romans worst defeats.
The disaster at Teutoberg was Rome's greatest defeat.The disaster at Teutoberg was Rome's greatest defeat.The disaster at Teutoberg was Rome's greatest defeat.The disaster at Teutoberg was Rome's greatest defeat.The disaster at Teutoberg was Rome's greatest defeat.The disaster at Teutoberg was Rome's greatest defeat.The disaster at Teutoberg was Rome's greatest defeat.The disaster at Teutoberg was Rome's greatest defeat.The disaster at Teutoberg was Rome's greatest defeat.
Some of the worst USN defeats and losses in US history; but the first US victory and the first Japanese defeat in WWII.
I would say the battle of Cannae (during the second punic war), where Hannibal's smaller force managed to surround and ultimately slaughtered the Romans.
The twin defeats at Camden, South Carolina (leading to the surrender of Charleston) were the worst defeats of the war in some ways. The series of defeats in and around New York City early in the war nearly ended the whole revolution. Taken together, the Battle of Brooklyn Heights (or Battle of Long Island), New York City, Harlem, Fort Washington, Fort Lee, and more, left about half of Washington's men captured or killed.
Not the worst, but one of the worst.
At port taco town
The British military commander who sustained one of the worst defeats in English history in 1755 in western Pennsylvania was General Edward Braddock. He led an expedition against French forces and their Native American allies during the early stages of the French and Indian War. However, Braddock's forces were ambushed and suffered a decisive defeat in the Battle of the Monongahela.
the battle of antietam
Yes it is widely considered to be the worst of the offerings for this vulnerability. It is also regarded as the worst performing offering.
The Battle of Fredericksburg was the worst defeat for the Union Army. It was General Ambrose Burnside's fault.
Gettysburg
The Battle of Savo Island.