As you may not be as experienced as some a bit of simple history might help. At the time your grandfather left Europe Posen was both a city and a county in the Province of Prussia which was in the German Empire. The population was a mixture of Germans and Poles. After the end of WW1 Poland regained its independence after having been divided up between The Russian, German and Austro-Hungarian Empires for more than 100 years and Posen reverted to the Polish name of Poznan. In 1939 the Germans invaded and occupied that part of Poland but in 1945 were driven out and Poland was re-established although with different borders because Stalin had grabbed the eastern half of the country and had no intention of giving up what he had taken. This meant the western Polish border was moved to the line of the Oder and Neisse rivers which you can see if you Google up a map of Poland today. During the years of German rule the towns and cities officially had German names although the Polish speakers would use the Polish names. Nowadays the city of Posen is Poznan in the Province of Wielkopolskie (Greater Poland), Hohensalza is Inowroclaw, north of Poznan near Bydgoszcz which was Bromberg under the Germans. I would suggest you Google these names, or some of them, which will help you to get the bigger picture. What looks like an "l" in Inwroclaw actually has a little line through it and is pronounced (very roughly!) a bit like a soft "w". Hope this helps a bit. Good luck with further searches.