Combined arms is an approach to warfare that seeks to integrate different combat arms of a military to achieve mutually complementary effects—for example, using infantry and armour in an urban environment in which each supports the other)

(Source)

The notion of combined arms is of cooperation of different kinds of military units, like infantry, armor, air power, and perhaps fire support from ships off shore, towards a single task or mission.

The Marine Corps has in recent history been the model of a service in which combined arms are deployed within the single service.

The Marine Corps has integrated infantry, armored forces, and both helicopters and fixed wing fighter aircraft, often with sea based support, in the same military service, rather than divided between separate military forces.

In contrast, for example, the U.S. Army receives its fixed wing fighter aircraft air support from the U.S. Air Force. Similarly, the U.S. Army generally relies upon the U.S. Air Force and U.S. Navy to be deployed to the theater of combat.

Within the U.S. Army, combined arms refers to the cooperation of infantry, armored vehicles, and sometimes armed helicopters, working together in a mission.

Fun fact: despite the fact that the U.S. Marine Corps seas amphibious assault is one of its core missions, the most famous amphibious assault in history, the D-Day Invasions, was a joint Army-Navy operation.

Combined arms is an approach to warfare that seeks to integrate different combat arms of a military to achieve mutually complementary effects—for example, using infantry and armour in an urban environment in which each supports the other)

(Source)

The notion of combined arms is of cooperation of different kinds of military units, like infantry, armor, air power, and perhaps fire support from ships off shore, towards a single task or mission.

The Marine Corps has in recent history been the model of a service in which combined arms are deployed within the single service.

The Marine Corps has integrated infantry, armored forces, and both helicopters and fixed wing fighter aircraft, often with sea based support, in the same military service, rather than divided between separate military forces.

In contrast, for example, the U.S. Army receives its fixed wing fighter aircraft air support from the U.S. Air Force. Similarly, the U.S. Army generally relies upon the U.S. Air Force and U.S. Navy to be deployed to the theater of combat.

Within the U.S. Army, combined arms refers to the cooperation of infantry, armored vehicles, and sometimes armed helicopters, working together in a mission.

Fun fact: despite the fact that the U.S. Marine Corps sees amphibious assault as one of its core missions, the most famous amphibious assault in history, the D-Day Invasions, was a joint Army-Navy operation.