“The Teutonic Knights were one some of the most despicable people to ever walk the face of the earth. “
Why?
One of the popular traditions of the Teutonic Knights was known as a Reis. A wealthy noble or knight from elsewhere in Christian Europe searching for adventure would travel to the Baltic coast to arrange one in exchange for funding the Order. This was a way for the Teutonic Knights to both raise money, influence, and manpower from those who chose to participate. What the Reis entailed can best be described as a human safari wherein knights would hunt Prussian, Lithuanian, or virtually any peasant in the area for sport. Think of the scene in planet of the apes where the apes on horseback are riding down the fleeing humans in the fields. Like that, except bloodier.
They attacked Christian dukedoms and principalities in the name of evangelization, falsely accusing them of being pagan when they in fact were not. Those they defeated, they also enslaved, even though they were Christian.
When recruiting troops in the West for their war against Poland in the 15th century, they would falsely tell recruits that it was for a crusade against a pagan kingdom, even though the Polish kingdom had been Christian since the 10th century.
All in all, they were a horrible, evil group of people who committed unspeakable atrocities in the name of Christ.
It is a pity King Jagelo of Poland did not completely wipe them out after winning his war against them. Instead, he signed a treaty with them and let them become vassals of the Polish crown. That was a big mistake.