- Birth of Donald Morden: The main antagonist of the series, Donald Morden, is born on January 24th, 1973 in New Brunswick, Canada.
- Birth of Ralf Jones: Ralf of the Metal Slug universe is born on August 25th in the USA.
- Birth of Clark Still: Clark of the Metal Slug universe is born on May 7th in the USA.
- Birth of Marco Rossi: Marco is born on April 13th in Idaho, USA.
- Birth of Tarmicle Roving: Tarma is born on May 1st in Hokkaido, Japan.
- Birth of Fiolina Germi: Fio is born on October 2nd in Genoa, Italy as the only female child of the wealthy Germi family.
- Birth of Eri Kasamoto: Eri is born on June 16th in Hiroshima, Japan. She is left alone in front of a church.
- Birth of Trevor Spacey: Trevor is born on June 25th in Korea.
- Birth of Nadia Cassel: Nadia is born on August 6th in France.
- Birth of Walter Ryan: Walter is born in an unknown date in Australia.
- Birth of Leona Heidern: Leona of the Metal Slug universe is born in January 10th in an unknown location of South America.
- Birth of Seirah: Whip of the Metal Slug universe is born in October 12th in Ireland.
- Birth of Tyra Elson: Tyra is born in an unknown date in the USA.
- A bombing on the Central Park by terrorists cause the deaths of many civilians, amongst them the son of Donald Morden.
- Donald Morden defects from the Regular Army and self-promotes to General.
- Morden organize the many terrorist groups and guerrillas into what became known as the Rebel Army.
- Start of the Rise of the Rebellion.
- The First Mission takes place.
- The First Modern War takes place.
- The Second Modern War takes place.
- The Third Modern War takes place.
- The Venusian Invasion takes place.
- The White Baby Crisis takes place.
- The Oguma Crisis takes place.
- The Garbage Island Incident takes place.
2XXX (Unknown date in the future)
- The remaining Rebel Army soldiers create a time warp and send their men, along with their futuristic weapons to the past, in order to help Morden launch a new coup d'etat.
Games in Chronological Order:
The games go chronologically as it follows: