Which battle was a decisive English victory during the Hundred Years' War?

While the Battle of Agincourt is indeed a significant English victory during the Hundred Years' War, the answer that specifically highlights a decisive English victory in that context is the Battle of Crecy.

The Battle of Crecy, fought in 1346, was one of the earliest major battles of the Hundred Years' War and is renowned for the effective use of English longbowmen, which decimated the French forces. This battle showcased the tactical ingenuity of the English army and marked a turning point in the war, establishing English dominance on the battlefield early in the conflict.

Although the Battle of Agincourt in 1415 is famous for its dramatic victory and the role of the longbow, Crecy is often emphasized as a foundational victory that set the stage for subsequent English successes, making it a quintessential example of English military superiority during the period.