Pepin the Short was the first of the Frankish noble family the Carolingians to be crowned King of the Franks. He was the younger son of Charles Martel, also recognized as a historically great figure. At first he and his older brother Carloman together ruled over Francia. Pepin controlled Neustria, Burgundy, and Pronvence, while Carloman controlled Austrasia, Alemannia, and Thuringia. However, Carloman eventually retired in 747 AD to live a purely religious life, leaving Pepin to be king over all of Francia, a decision supported by Pope Zachary in 751 AD ("Pepin the Short").
While Pepin is generally not considered to be as great as his father nor as great as his son Charlemagne, he is considered great in his own way. For one thing, after his father started building up a heavy cavalry, meaning soldiers on horseback, Pepin followed in his footsteps by making the cavalry even larger and stronger. Using his army, Pepin, like his father, continued to keep the Iberian Muslims from invading and drove them out. He even managed to put an end to battles between the Aquitanians and the Basques that had lasted for three generations. After conquering the Aquitanians and the Basques, he was able to continue expanding the Frankish church into southern Gaul and Muslim Iberia, now Germany and Scandinavia, just as his father had wanted. He even initiated feudalism, a system of government Europe evolved around all through the Middle Ages ("Pepin the Short: Legacy").
Just as an add-on, Pepin the Short was not known for his great military prowess, but nontheless, he was undefeated in battle during his lifetime.