Great surprise from Ekaterina

This is very special card for me. I received it from Ekaterina from Belarus as thank-card. it's really important, because Ekaterina wrote the truth, that belarus and Poland are very close neighbours and have got many common moments in history. Those card and stamp show this community: it's crest of Ludwika Karolina Radziwillowna and stamp is about one of the most important battle in our history - The Battle of Grunwald from 1410.
Thank you very much!