The 1856 Last Island hurricane (also known as the Great Storm of 1856) was a deadly and destructive tropical cyclone that is tied with Hurricane Laura and Hurricane Ida as the strongest hurricane on record to make landfall in the U.S. state of Louisiana, as measured by maximum sustained winds. The first known tropical cyclone of 1856 Atlantic hurricane season, it was observed first as a minimal hurricane in the Gulf of Mexico near Dry Tortugas on August 9. Moving northwestward, the cyclone quickly intensified into a strong Category 4 hurricane on the modern-day Saffir–Simpson scale by the following day. Late on August 10, the hurricane made landfall on Last Island, Louisiana, with winds at 150 mph (240 km/h), hours before striking near New Iberia. The system rapidly weakened after moving inland, falling to tropical storm intensity on August 11. The storm would be last noted over Mississippi on the next day.

Offshore, at least 183 people drowned after steamers and schooners sank in rough seas produced by the hurricane. A storm surge between 11 and 12 feet (3.4 and 3.7 m) completely submerged Last Island in Louisiana, destroying virtually every structure, including the hotels and casinos, while all crops were ruined. Additionally, Last Island itself was split in two. Inland, heavy rainfall caused the Mermentau River to flood, destroying crops and every house in Abbeville. The storm produced as much as 13.14 inches (334 mm) of precipitation in New Orleans. In Plaquemines Parish, rice fields were under several feet of water, while many orange trees lost their fruit. Overall, the hurricane resulted in at least 200 fatalities.