From HowStuffWorks.com comes a book chock full of information about the US military and its special units, including their work, their training, and what it takes to be among the best of the best
SEAL Team Six. Army Rangers and Delta Force operators. Green Berets. Who are these highly specialized soldiers? They are the elite units within the US military. They are trained for the performance of extraordinary tasks to preserve peace and protect the United States. 
Most citizens have heard of the five main branches of the US military: the army, the navy, the air force, the marines, and the coast guard. And those men and women work diligently and bravely to protect our nation. But periodically, news breaks of an uncommon event, like the killing of Osama bin Laden or the Battle of Mogadishu. The startling complexity and delicacy of these operations indicate the intense preparation a smaller group of exceptional soldiers must undergo. The warriors who perform these higher-level operations come from the special-forces teams known as Army Rangers, military snipers, Green Berets, Navy SEALs, and the shadowy Delta Force.
Learn about their selection and training, the origins of their unique specialties, and their mission and purpose. Learn what it takes to be truly elite in Green Berets, Blackhawks, Purple Hearts: Elite Units of the US Military.