Why "Drang nach Osten"?

“Drang nach Osten” (Drive to the East), seems to be a prevalent theme in German history. It was behind Hitler’s failed Operation Barbarossa, and it goes back to the time of the Teutonic Knights-who fought several wars with the Slavic peoples of the Baltic Region. What’s the origin of this? Wasn’t Germany big enough? Or was it because the Germans came late to the Crusade-party, and felt there was fame and fortune to be won by conquest in the east? Was Germany always in conflict with the Poles?
I was reading a recent NY times article, about the Polish city of Gdanya (Gdansk); they brought up the fact that the city was originally settled by Germans- only later did the city become polish.
Anyway, do the Germans of today still cast longing eyes to the east?

Referring to your last question:

Modern Germans are still aware of the fact that the Western part of Poland was German throughout most of its history, but apart from Neo-Nazis, nobody seriously demands these areas back for Germany. That hasn’t always been like this; after WWII, almost the entire German population of these areas transmigrated westwards to what is now the Federal Republic of Germany, and currently there’s a hot debate about this - is it adequate to call this a “Vertreibung” (displacement) or even a crime committed by the governments of Poland and the other states to the east of Germany?

During the 1950s and for many years to come, the conservative (not necessarily Neo-Nazi) groups (most prominently the now governing CDU party) in West Germany made it clear in their statements that they regarded these areas as German. West German maps showed these areas as being “under Polish (or, in the case of the Königsberg/Kaliningrad region, Soviet) administration”, implying that in fact they were German, although preliminarily not under German control. The border between West and East Germany and the border between East Germany and these areas was usually just a line of dashes, drawn less clearly than “ordinary” national boundaries. The East German government, however, officially ceded these areas to Poland and Russia as early as the 1950s and made no further claims.

The position in West Germany changed under the administration of Chancellor Willy Brandt and his policy towards the Eastern bloc. He concluded the Basic Treaty with East Germany, which was the first time that West Germany accepted the existence of two German states, and abandoned the West German government’s claim to represent all Germans. Brandt also concluded treaties with Poland and the Soviet Union, abandoning the claims that the areas east of the Oder and Neisse rivers were German.

After the reunification of 1990, Germany again concluded treaties affirming this. Now, the official position of Germany is that the areas east of the Oder and Neisse are not German any more, and, as I’ve already said, nobody (except for the Nazis still dreaming of the Reich), casts longing eyes to these regions. In fact, somebody making claims about the “German” character of these territories will quickly be regarded as a right-wing radical by other Germans, so this is not an issue any more.

There are associations of people who populated these regions until after the war, and these associations still celebrate their heritage; they have some sort of political influence, because the conservative parties traditionally woo them, but for demographic reasons, their importance is dwindling, and most Germans nowadays regard these associations and their continous rallies as a nuisance.