Ottoman scouts report to Suleiman that there are untouched villages near Vaslui, and the Ottomans head for that region.
The winter makes it difficult to set camp, which forced the Ottomans to move quickly and head for the Moldavian capital, Suceava.
In order to reach Vaslui, where the Moldavian army had its main camp, they need to cross Podul Înalt over the Bârlad River.
The bridge is made of wood and not suitable for heavy transportation of troops.
Stephen chooses this area for the battle—the same location where his father, Bogdan II, had defeated the Poles in 1450; and where he, at seventeen, had fought side-by-side with Vlad 'the Impaler'.
The area is ideal for the defenders: the valley is a semi-oval surrounded on all sides by hills covered by forest.
Inside the valley, the terrain is marshy, which restricts troop movement.
Suleiman has full confidence in his troops and makes few efforts to scout the area.
The battle begins on the rainy morning of January 10.
The weather is frigid, and a dense fog limits vision.
The Ottoman troops are exhausted.
Stephen fortifies the bridge, while setting and aiming his cannons at the structure.
Peasants and archers are hidden in the forest, together with their Prince and his boyar cavalry.
The Moldavians make the first move by sending musicians to the middle of the valley.
The sound of drums and bugles makes Suleiman think that the entire Moldavian army awaits him there.
Instead, the center of the valley holds the Székely forces and the Moldavian professional army, which have been instructed to make a slow retreat when they encountered the enemy.
Suleiman orders his troops to advance and, when they make enough progress, the Moldavian artillery startd to fire, followed by archers and handgunners firing from three different directions.
The archers cannot see the enemy for the fog, and, instead, have to follow the noise of their footsteps.
The Moldavian light cavalry then helps to lure the Ottoman troops into the valley by making hit-and-run attacks.
Ottoman cavalry try to cross the wooden bridge, causing it to collapse Those Ottoman soldiers who have managed to survive the attacks from the artillery and the archers, and who have not become caught in the marshes, have to confront the Moldavian army, together with the Székely soldiers further up the valley.
The five thousand Székely soldiers are successful in repelling the seven thousand Ottoman infantrymen.
They then make a slow retreat, as instructed by Stephen, but are later routed by the Ottoman sipahi, while the remaining Ottoman infantry attacks the Moldavian flanks.
Suleiman tries to reinforce his offensive, not knowing what had happened in the valley, but then Stephen, with the full support of his boyars, orders a major assault.
All his troops, together with peasants and heavy cavalry, attack from all sides.
Simultaneously, Moldavian buglers concealed behind Ottoman lines start to sound their bugles, and in great confusion some Ottoman units change direction to face the sound.
When the Moldavian army hits, Suleiman loses control of his forces.
He desperately tries to regain control, but is later forced to signal a retreat.
The battle lasts for four days; with the last three days seeing the fleeing Ottoman army being pursued by the Moldavian light cavalry and the two thousand-strong Polish cavalry until they reach the town of Obluciţa (now Isaccea, Romania), in Dobruja.
The Ottoman casualties are counted as forty-five thousand including four Pashas killed and a hundred standards taken.
Jan Długosz writes that "all but the most eminent of the Turkish prisoners are impaled", and their corpses burned.
Only one is spared—the only son of the Ottoman general Isaac Bey, of the Gazi Evrenos family, whose father had fought with Mircea the Old.
Another Polish chronicler reported that on the spot of the battle huge piles of bones rested upon each other, next to three immured crosses.
