A term with a few different meanings, depending on the context of its use.
The Huns were a tribe of Asiatic nomads who, under the leadership of Atilla the Hun (also known as the "Scourge of God" by Europeans who feared him) in the 5th century
AD, swept into Europe with his infamous horde of mounted archers. Under his leadership, they pillaged/sacked/razed many towns and villages belonging to the Roman Empire, and other tribespeople who were in Europe at the time (namely the Germanic tribes). Relatively little is known about this group of
people.
The term resurfaced in the early 20th century, when WWI broke out. By the Allied powers, it became a derogatory term for any German
soldier (much
like "Fritz" and "Jerry" were also used to refer to Germans). It stayed in use as late as WWII. It was akin to the terms "
Tommy" (for
English soldiers) and "Yank" (for US soldiers).
The Huns swept through Europe, threatening
Rome and
local tribespeople.
"C'mon, you Hun bastards, get outta your
fucking dugouts! I got a hundred Maxim rounds with your names on them!"