Also known as First Battle of Tannenberg. One of the largest battles in Medieval Europe that started the decline of Teutonic Knights. Polish and Lithuanian forces met the Teutonic Order army near the villages of Grunwald and Tannenberg. It’s hard to determine the exact numbers of soldiers involved, but the approximates are about 30,000 Teutonic Order knights and their allies, about 40,000 on Polish-Lithuanian forces.
The technological advantage was on the Order side - they had archers, crossbowmen and artillery. Before the battle they have prepared hidden pits that attacking army would fall into, but the Polish forces didn’t come as expected to the battlefield. They were kept in the woods, so the emissaries of Teutonic Order were sent to Polish king and offered him two swords (for him and the Lithuanian prince) so they would stop hiding and come to the battlefield.
In the first part of the battle Polish king sent the Lithuanian light cavalry, which wasn’t affected by the pits, which forced the Teutonic Order to send their cavalry earlier than planned and they had to overrid the archers. When the heavy cavalries have joined the fight Lithuanian cavalry that dragged the enemy into the battle regrouped, flanked the battlefield and attacked the enemy from behind, which started the defeat of Teutonic Order.
The tensions between Polish Kingdom and Teutonic order leads to one of largest battles of medieval Europe.