Assault on Copenhagen Day is observed in Denmark every February 11, commemorating the significant battle that took place on this date in 1659 during the Second Northern War. This day marks the successful defense of Copenhagen against Swedish forces, which attempted to conquer the city after a failed siege. The celebration includes a flag hoisting ceremony, as the state flag is raised in honor of this military victory. The assault was initiated by King Charles X of Sweden, who faced heavy losses, with around 600 Swedish soldiers counted dead compared to only 14 Danish casualties. The event highlights Denmark's military history and resilience, and it is recognized as a military flag-flying day in the country.