Saw the movie “Jarhead” tonight, about a group of marines stationed in the middle of the desert in the first Gulf War. Whatever other factual inaccuracies it may contain, assuming that it was accurate in its portrayal of where the Marines were stationed, why were there Marines in the desert in the first place? There wasn’t a single shot of ocean or sea in the movie. I had been under the impression that the Marines were the ones who attacked the land from the sea. If not, what could they do on the land that the Army couldn’t already do?
Generally speaking, the Marines are geared towards fast strikes. They take territory, as opposed to the Army which is more geared towards taking and holding territory.
I have a friend who was a jarhead in the first gulf war. He was stationed in the desert. He was a mechanic who supported the first group of marines that went up into Kuwait. Marines were part of the first push into Kuwait at the start of the ground war, and he followed the main battle group up the road into Kuwait.
So yeah, they were definately in the desert.
The modern function of the Marine Corps, as called for in their purpose statements, training materials, and the like, is to be an elite force capable of moving in rapidly in the face of the enemy and securing an area. While they are an autonomous branch of the Department of the Navy and do have duties relative to the Navy, including providing ships’ garrisons and handling amphibious landings, they are also intended to act as a rapid strike force, wherever one is needed. (The fact that the Army has similar rapid-deployment forces, such as airborne and light infantry, is not duplicative but complementary to the Marine role.)
One is tempted to point out that one of the biggest Marine Corps bases in the country is smack dab in the middle of the Mojave Desert (well, not in the middle of it, sort of on the border of the Mojave and Sonora Deserts, but you get my idea). 
As an old[ ww2] jarhead I will never forget the DI who said that when he finished with us we would ,“Charge hell with a bucket of water,ask no questions about who or why, and continue on until the job was done!”.
Assault troops?------yes indeed!
General duty troops?----------yes,absolutely!
Did we back up army units and relieve them?------------yes.
Did they do the same for us?-------Yes.
Are the two services vital to each other?--------damned right.
All that stuff about who should be doing what is a lot of schoolboy rah rah stuff.
When a fire fight is on all you ask of the guy next to you is that he be shooting ion the same direction that you are,no matter what hunk of brss he has pinned on is tabs!.
Or,looking back,so I believe!
EZ