"Beyond the Black River" by Robert E. Howard is a short story first published in May–June 1935. Set in the fictional Hyborian Age, it follows Conan the Cimmerian as he battles a savage Pictish tribe led by the wizard Zogar Sag in the unsettled wilderness beyond the Black River. When a frontier fort faces overwhelming assault, Conan and a young settler named Balthus must warn defenseless colonists before they're slaughtered in a massive raid that threatens to reclaim an entire province. (This is an automatically generated summary.)
These books are free to read. Each is in the public domain in the United States; check your own country's rules before you copy or share one.