The Battle of Jengland occurred between the forces of Erispoe, Duke of Brittany, and Charles the Bald, King of West Francia. Tensions had been escalating as Charles sought to assert his influence over Brittany, a region increasingly seeking autonomy in the face of Carolingian pressures. Erispoe was motivated to defend Brittany's sovereignty and push back against Frankish incursions. In August 851, the two armies clashed near the Breton town of Jengland, where Erispoe’s forces, employing tactical maneuvers, ultimately outmaneuvered Charles’s troops, leading to a significant victory.

This confrontation was not only a military engagement but also represented the broader struggle between the Carolingians and the Breton nobility. Erispoe's victory enabled him to affirm his authority and strengthened the position of Brittany as an independent entity within the fractious political landscape of medieval France. The battle's outcome resulted in the retreat of Charles, underscoring the challenges faced by the Frankish monarchy in maintaining control over peripheral territories.

In the aftermath, Erispoe consolidated power in Brittany and fostered alliances that would enable greater autonomy. The defeat of Charles the Bald at Jengland diminished his reputation as a ruler able to maintain order in his realm. This battle thus played a critical role in shaping the future of both Brittany and the surrounding regions, and marked a rare instance of successful resistance against the Carolingian Empire by an independent duchy.