Oldest Firearm in the US, A 500-Year-Old Cannon Unearthed in Arizona, Reveals Native Victory Over Conquistadores

5/2/2025

In the southern Arizona desert, a fragment of forgotten history has emerged from the dust: a bronze cannon, silent for nearly 500 years. This relic is officially the oldest firearm ever found in the continental United States. It was unearthed at the site of San Geronimo III, a doomed settlement established during the Spanish conquest in 1541.

This cannon tells a story of conquest, resistance, and one of the earliest Native American victories against European colonizers.

The Town That Vanished

In 1540, Francisco Vázquez de Coronado led 400 soldiers, their families, and about 1,500 Indigenous allies northward from Mexico. They sought the fabled “Seven Cities of Gold.” It was a grueling journey. They drove herds of livestock across mountains and deserts, relying on sparse water sources and limited supplies. By 1541, they had reached southern Arizona, where they established a settlement they called San Geronimo III, or Suya.

San Geronimo was the first European town in the American Southwest. Coronado left behind 200 to 400 people — soldiers, servants, and settlers — to build a permanent presence for the Spanish crown. So, they constructed adobe and rock buildings, tended to the sick, and defended the settlement’s perimeter with walls and firearms like the bronze cannon. But what they envisioned as a foothold for Spain was, in truth, a powder keg.

The Sobaipuri O’odham, who farmed the rivers of southeastern Arizona, were no strangers to outsiders. But the arrival of the Spanish brought abuses that ignited tensions. The conquistadors seized food, enslaved women, and punished dissent with mutilation. Noses, tongues, and hands were cut off for minor offenses. These transgressions did not go unanswered.

In the predawn hours of one fateful morning in 1541, the native Sobaipuri launched a surprise attack on the town. Accounts differ on the details, but the result was catastrophic for the Spanish. Many settlers were killed in their beds, and the survivors fled in disarray. One story tells of a priest wielding a broadsword in a desperate defense, who managed to save six Spaniards. Still, the cannon — meant to intimidate and protect — was never even loaded.