The Riders of Falcon Hold are primarily a ground-based army.  They maintain no navy, but have combined forces with naval organizations when needed. 
There are main companies, which are primarily infantry but include light cavalry, engineers, and at least one or two magical members.  There is also a specialized engineering company, two heavy cavalry companies, and a magical “company” that consists of only a single, very well-regarded squad.  Those provide the bulk of the Riders’ military might.  But the original adventurers knew the limitations of conventional military forces.

Besides the soldiers, there is one special company called the Peregrines.  The Peregrines are not trained to fight, although all of them have some combat training.  They are messengers and scouts par excellence.  In fact, they make good money for the company by selling their services for mail delivery and the like when they aren’t needed for the Riders.  Another non-standard branch is the Kestrels, who are spies and diplomats.  (Some soldiers grumble that those are two words for the same thing.)  There is some friction between the Kestrels and the rest of the Riders since the Kestrels are trained in Waterdeep, and often seem to have their own agenda.

Finally, the Riders of Falcon Hold maintain a variable number of “Free Talons.”  A Talon is the smallest fighting force the Riders train, usually from four to eight men.  A Free Talon is a Talon not connected to any squad or company.  The members are often drawn from many branches of the army.  Their missions are the least “military” of any.  In fact, they are basically adventurers themselves.  Some even pursue freelance work alongside their service to the Riders.