[1] Situated on an elevated bank near the river junction about 100 kilometers (62 mi) from the capital city of Vilnius, it served as a strategic outpost.

During this attack, the Knights constructed a siege tower and erected wall-penetration machinery; primitive firearms might have been used since gunpowder technology was emerging in Europe.

According to Wigand of Marburg, the castle's garrison consisted of about 400 Lithuanian soldiers, commanded by Vaidotas, son of Duke Kęstutis.

In any event, Kęstutis soon regained and rebuilt Kaunas Castle, but it remained a point of contention between Lithuanians and Teutonic Knights for many years.

At this time, Grand Master Konrad Zöllner von Rotenstein began the reconstruction of Kaunas Castle and renamed it Marienwerder.

Upon completion of construction the Castle was adapted for withstanding the most up-to-date wall breaking techniques of the time.

Following the Battle of Grunwald, Kaunas Castle began to be used mainly as a residence and an administrative centre of state affairs.

The Elder of Kaunas (seniūnas), title created in 1398, was tasked to preside over the castle and allowed to reside here.

In confluence with the city being granted the Magdeburg rights in 1408, castle became the core centre of the Kaunas Powiat [lt] administration.

The castle's stature in serving the Grand Duchy's administrative purposes diminished after the death of Vytautas.

During the 16th century, the castle was strengthened and adapted to new defensive purposes by constructing an artillery bastion near the round tower.

The evidence gathered from these archeological works suggests that the castle's configuration, excluding the bastion, has remained in the form it took during its reconstruction in 1376.

Kaunas' city and castle were mentioned in the famous Lithuanian[3][4] and Polish poet Adam Mickiewicz poem Konrad Wallenrod (1828), set in the 14th-century Grand Duchy of Lithuania.