A tale of two small cities in Poland

Take a look at this cover. It was sent in February 1824 From Warsaw to France. It has 5 postal markings, in order:

• A Warsaw postmark
• A Strzalkowo postmark
• T.P. which stands for "Transit Prusse" or Prussian transit
• R.No.5. This is worth a blog all by itself but briefly, it means the French regarded it as an unpaid letter from Prussia's 5th Raion - that part of Prussia the furthest removed from the French border
• Prusse Par Givet: a French marking (actually applied in Paris)  simply denoting that this Prussian letter had entered France at Givet, and that French internal postage was to be calculated from Givet to its destination, Rheims.

Since the Strzalkowo postmark is similar to the Memel postmarks you see on many Russian letters from this period you might conclude that this is a Prussian postmark, and that it denoted where the letter entered Prussia. You would be right. Since Strzalkowo is in Prussia's 5th Raion, that also fits with the R.No.5 marking. Apparently Polish domestic postage had been prepaid but after it left Poland it was all unpaid. The "17" is the final charge to the addressee of 17 decimes. 

Strzalkowo is still around: you'll find it due West of Warsaw and yes, the Prussian border really used to be there. It wasn't until 1945 that Poland was forcibly relocated a few hundred kilometers to the West.

Now take a look at this letter:

This letter, from February 1818, went from Warsaw to Leipzig in Saxony. It has a similarly Prussian-looking postmark of Slupce. Slupce is now called Slupca and it is right next door to Strzalkowo, about 4 kilometers closer to Warsaw. What's going on?

The postal history of Poland in the 19th century is as complicated as its history. Recall that Napoleon had re-created a "Grand Duchy of Warsaw" as a rump Polish state. After Napoleon's defeat, the Vienna Congress decided to once again slide and dice Polish lands between Russian, Prussia and Austria, but the Russian share was made into a Kingdom of Poland, which just happened to have the Russian Tsar as its king. Poland  had an independent postal system from the moment of its rebirth, and it slowly got going in 1817. At the time, Slupce was in Prussia and it was the Prussian entry point for westbound mail from Poland. However, in 1817, Prussia and Poland (re)defined the border between the two states more exactly, and by that treaty (signed in late 1817 and ratified in February 1818) Slupca became Polish and Strzalkowo became the new Prussian entry point for Polish mail. So for a very brief period (about February 1817-March 1818) you will see a Prussian Slupce as entry marking for Polish mail, and after that, Strzalkowo takes over.

The best literature on this stuff is probably the series of articles written by Ilse Popp for the Deutsche Altbrief Sammler-Verein. They're impossible to find, but priceless.