Mexican Independence Day is celebrated on September 16.
It commemorates the Grito de Dolores (Cry of Dolores) of 1810, which sparked the Mexican War of Independence.
On September 16, 1810, Roman Catholic priest Miguel Hidalgo y Costilla rang the bell, gathering his congregation in the small town of Dolores, and addressed the people in front of the church, encouraging them to revolt against the Spanish colonial authorities.
This address became known as the Grito de Dolores.
Although Mexico officially gained dependence in 1821, after eleven years of war, it is the anniversary of the Grito de Dolores that is marked as Mexican Independence Day.