On this day July 23, 1343, Casimir the Great in the town of Kalisz signed a peace treaty with a band of tough dude knights which gave away Pomerania and ensured that his country could have a chance at tranquility, unity, and access to the sea.
Toward the end of the 13th century, Poland was divided into increasingly small duchies. This division (what we now call Balkanization) was a hassle for everyone except the dukes who controlled the parcels. The Catholic church found it to be a bother because their diocese borders were not the same as the provinces. Every petty tyrant wanted to be important and make businesses pay extra for trade. Warsaw did not even belong to Poland. Foreign invaders could just walk in and take a small duchy and no one would come to their aid. Who would want to build a town in a place like that? It was a mess.
Don't get me wrong, there was a real perception of the need to unify. Problem was, who was going to do it and take credit? Like rival street gangs, everyone knew outside boys were going to bust their chops but who should rule the place: Crips? Bloods? Warriors? Baseball Furies? The Church? Knights? Nobility? Burghers?
While all of this thinking was going on, Gdansk Pomerania was seized by the Teutonic Knights in the years 1308-1309. The loss of Pomerania and of Poland's access to the Baltic Sea were ominous events, as they ushered in a long period of wars between Poland and the Teutonic Order for the recovery of those territories. As we saw with the former Soviet Union, access to the sea is a very important thing for any country who hopes to trade with others at a distance.
During the first few decades of the 14th century, Poland was the weakest of those sovereign kingdoms facing a constant threat from the alliance between the Czechs and Teutonic Knights. Ladislaus the Short, King of Poland, in his struggle to recover Pomerania, took advantage of the Pope's support and of the alliance with Hungary, but neither a court trial before the papal envoys, which he won, nor an armed struggle, brought the desired effect. Sometimes one must think in different directions.
His son and successor, Casimir [Kazimierz] the Great (1333-1370), one of the most outstanding Polish rulers, made peace with the Teutonic Knights on this day in 1343, giving away Pomerania as "an eternal alms" to them. By giving that, he then could bargain for the recovery of other lands held by the Order. He also made John of Luxembourg give up his claim to the Polish crown. Okay, he had to give Silesia on Poland's western border over to Bohemia. Nothing comes for free.
Once Poland was at peace, Casimir got to work encouraging new villages and towns. He promoted trade and helped get some rules for extracting salt, lead, silver and iron. He established a unified state currency which just had to help trade. As far as governing, he included lots of folks on his advisory counsel and actually listened to them! He actually separated the concept of the crown and the king - something folks in some medieval recreation groups have yet to understand completely. He set up border-guarding castles and reformed the army. Heck, he even sponsored the first Polish university, the Krakow Academy in 1364.
Toward the end of Casimir's reign, the population of Poland was about 2 million. The population density increased by at least a factor of 2 from a century or two before. Polish culture diffused to over one million folks outside its borders. Within the kingdom Jews, Germans Ruthenians all lived with native Poles.
Casimir had no lawful son. He concluded a treaty with Louis Angevin, the King of Hungary, so that when Casimir died the crown went to Louis. Louis eventually bartered away many privileges to Polish knights (not the Teutonic ones) in order to secure the recognition of one of his daughters as an heir. Well, knights need stuff, too. Rather sweet, actually, that he wanted his daughter to reign.
What have we learned from this? Access to the sea is everything? Everybody wants to rule Gdansk? Sometimes it pays to think outside the Czechs? Caring means sharing? How about a country generally does lots better when it is at peace? King, Rodney said it best, "Can't we all just get along?"