Alternative History
Cygnian Imperial Marine Corps
Seal of the Cygnian Imperial Marine Corps.png
Seal of the Cygnian Imperial Marine Corps
Founded 10 November 1785 (235 years ago)
Country Eureka Flag.svg Cygnia
Type Marine combined arms
Role Amphibious, expeditionary and aerial warfare
Size 182,000 active duty personnel
38,500 reserve personnel
1,200 aircraft
Part of Ministry of Defence
  • Department for the Navy
Headquarters Defence Complex, Northam, TS
Motto "Per Mare, Per Terram" (Latin)
"By Sea, By Land"
Engagements Cygnian War of Independence
World War I
World War II
World War III
Indian War
Persian Gulf War
War on Terror
Website www.marines.mod
Commander-in-Chief Queen Elizabeth
Minister for Defence Richard Marles
Secretary for the Navy Arthur Langley
Commandant Major General Robert Magowan

The Cygnian Imperial Marine Corps (CIMC), also known as the Imperial Marines, is a branch of the Cygnian Imperial Armed Forces responsible for providing power projection, using the mobility of the Cygnian Imperial Navy, by Congressional mandate, to deliver rapid, combined-arms task forces on land, at sea, and in the air. The Imperial Marine Corps is one of the four armed service branches in the Cygnian Ministry of Defence (MoD) and one of the six uniformed services of Cygnia.

The Marine Corps has been a component of the Cygnian Department for the Navy (earlier the Ministry of the Navy) since 30 June 1834, working closely with naval forces for training, transportation and logistics. The CIMC operates posts on land and aboard sea-going amphibious warfare ships around the world. Additionally, several of the Marines' tactical aviation squadrons, primarily Marine Fighter Attack squadrons, are also embedded in Navy carrier air wings and operate from the Navy's nuclear-powered aircraft carriers.

Two battalions of Royal Marines were formed on 10 November 1785 in Perth as a service branch of infantry troops capable of fighting for independence both at sea and on shore. The role of the Corps has since grown and evolved, expanding to aerial warfare and other fields. The Imperial Marine Corps has distinguished itself as it has served in the majority of Cygnian wars and armed conflicts, from its inception to the modern era, and attained prominence in the 20th century when its theories and practices of amphibious warfare proved prescient and ultimately formed the cornerstone of the Pacific theatre of World War III.

By the mid-20th century, the Cygnian Imperial Marine Corps had become a major theorist of and the world's dominant practitioner of amphibious warfare. Its ability to rapidly respond on short notice to expeditionary crises gives it a strong role in the implementation and execution of Cygnian foreign policy. As of 2016, the CIMC has around 182,000 active duty members and 38,500 reserve personnel, making it the smallest of the Imperial Armed Forces.