US Cavalry. Bonus fighting against civ states (i.e. "injuns!"). Greater speed when moving over territory not belonging to anyone. Settlers can stack with it, thus can zip around quickly.
There's a nickname of US Army Cavalry. The 'Yellowlegs'
They prefer Mounted Infantry actions like 17th Century Dragoons. This due to their origins with their historic parent empire--British Empire, deployed Light Dragoons in North American Theatre whenever there's war particularly against either Natives or another European Rivals (Particularly France) and later Revolutionary war in 1777-1792 (16th and 17th Light Dragoons Regiments), and even in War of 1812 that British Light Dragoons retained original functions of Dragoons (and Cavalry as a whole) by that time period while everyone else in Europe abandoned these functions and focus entirely on Knightly Charges especially after 1740 when King Frederick II of Prussia demanded (and instructed) EVERY Prussian Cavalry regardless of labels to charge as a regiment and discard mounted infantry actions entirely.
There's reasons British Army retained mounted infantry in their Light Dragoons--one of these included that Britain of 18th Century was running North American colonies, Bushy and hilly terrain of Eastern Portions of North America, particularly those within what's now the original states of the USA. the terrain suits shooting better and not the same cavalry charge as in continental Europe, so horses are mode of transportations only, even with Dragoons of that time were trained with swordsmanship in the same standard as other Cavalry, there were not so many cavalry charge with rattling sabers in North American Theatre throughout 18th Century, instead British Light Dragoons focused on shootings (This worked better in that theatre, particularly against Natives), with them issued rifled carbines while everyone else in Europe of that time tended to equip their carbine cavalry with smoothbore variants. This influenced American cavalry tactics as a whole since the American Revolution.
In Addition to this, Horse ranches in North America were not yet capable of breeding and raising big and muscular Desteriers (or similiarly big warhorses able to support Cuirassiers), let alone maintaining ones, and even in Britain, ranches that could breed and raise big warhorses were not so common (they have to import ones from Continetal Europe maybe?), British warhorses tended to be slightly bigger or slightly better than peasantry workhorses, to this end British (as well as English of the Middle Ages) favorted mounted infantry tactics even their knights favored dismounted combat over chargings, with this shortcomings, heavy chargers aren't ideal, despite that there were Polish Lancers (Heavy Cavalry) serving Continental Army, this didn't last long though, this summarized American cavalry doctrines to follow examples of British Light Dragoons. In the War of 1812, the only two US Army Cavalry regiments were labelled as Dragoons and not something else, regardless of what labels the US Army gave to each regiments (Cavalry, Dragoons, and Mounted Rifles) everyone fight like British Light Dragoons and favors rifled carbines from the beginning, in 1830s their gunslinging doctrines are reaffirmed with Samuel Colt introduced the first mass produced revolvers, one of earliest buyers were cavalry, and this new invention proved successful against enemy heavy cavalry charges (against Mexican Lancers and Cuirassiers, Great Plains and Western Native Lancers). This reaffirmed American cavalry tactics to be firearms heavy even when chargings they tended to use revolvers rather than or before saber rattlings.
What does in means in game terms? Anticavalry malus don't apply to this unit.
But personally the Yellowlegs aren't unique to him. Monitors, Sharpshooters, and Rifled Cannons, all of these that emerged in his tenure as presidency or saw extensive deployment there, should be his.
