The U.S. Navy has activated the first three squadrons of its new amphibious force. While not replacing the U.S. Marine Corps (which has evolved from a small part of the navy, in to an independent service, over the last century), the new Naval Expeditionary Combat Command will eventually have 40,000 sailors. The first three squadrons will consist of about 700 sailors and 36 armed boats. The boats of the three squadrons will be used for patrolling rivers and coastal waters, or moving up to 600 troops (marines or army) at a time. While the marines developed most modern amphibious warfare techniques over the last 70 years, the army has actually made more amphibious landings. This was especially the case during the Vietnam war, the last time the navy had a "brown water" force. In that war, an army infantry brigade, supported by sailors, and their shallow draft boats, made hundreds of amphibious landings over several years. The Vietnam era brown water navy also put SEALs and marines ashore, but not nearly as often as they moved army troops. During World War II, the army also had a fleet of transport ships and coastal boats. Actually, in sheer numbers, the army fleet had more ships than the navy did. But that changed after World War II, and the navy wants to make sure the army doesn't get into the boat business again. The army does have a few boats, mostly for army engineers to use when building temporary bridges. But the army trains its troops to use these boats for amphibious assaults across rivers.