Want to conquer Europe in the Middle Ages? You need plenty of knights mounted on steeds to launch a full cavalry charge. Once they take out their enemies in pitched battle, you need engineers to launch a siege on your enemies’ castles.
Want to conquer Europe in 1600? Everything has changed. Cannon makes castles obsolete. Firearms and pikes have displaced knights as the dominant force on the battlefield. The scale of war has also grown from a few thousand soldiers on the battlefield to tens or even hundreds of thousands of pikemen, cavaliers, and armed infantry.
To explain this change that has happened is Patrick Wyman of the Tides of History Podcast. Patrick is a medievalist by training and explores how events in the far past still have influence today.