Erul the Lame, aka Erul Oakfoot, was a great clan karl (like a chief or jarl) who rode a large black stallion believing its height and breadth made him more fearsome. Well it did until it cost him his left foot.
He attempted to ride down a battleaxe-wielding enemy who didn't break and run as all other men before had. Instead the warrior took one last mighty swing before being crushed beneath the pounding hooves of the warhorse. The swing hacked off Erul's foot and dealt the horse a mortal blow, crushing its ribs into its lungs. Erul survived and was fitted with an oaken foot that now clumps and echoes through the halls of his stronghold.
His son, Eronan the Bold learned from his father's tragic lesson and now literally stands his ground in battle. He leads from the front with his standard bearer and has vowed that, while possessing heavy cavalry, he will never ride into battle himself. He may ride to the front lines, but he will not fight from horseback because he finds it ungainly and exposed.