The Germans oppose the treaty of Versailles because the agreement was unfair to them. The terms of the treaty were harsh and the Germans suffered deep humiliation.
Since the Germans had not been involved in negotiating the treaty, a feeling developed in Germany that they were under no moral obligation to obey its terms. They called it a 'diktat' (dictated peace) because it had been imposed on Germany. The German government had sign the treaty but had not agreed to it. The Germans had no say in drawing up the treaty so they could feel free to ignore its terms.
The Germans were seen as being responsible for the war and it followed that they should be made to pay for it. Germany was told it would have to pay compensation or reparations to the Allies for the war damaged caused. The Big Four could not agree on what the bill was to be, so the treaty set up a commission to decide the exact amount.
The German government objected, saying that this was like being asked to sign a blank cheque. However, they were forced to accept it. The commission reported in 1921, setting reparations at ÃÂ£6,600 million, partly in money and partly in goods. Most of this was to go to Belgium and France. Germany will loose all its colonies which would all became mandates of the League of Nations. This meant that they would be run by one of the victorious powers until they were ready to receive independence.
Other reasons were the humiliation of the Germans. In the war guilt Clause, it stated that Germany accepted the blame for 'all the loss and damaged which the Allied governments and their nationals have been subjected to as a consequence of the war imposed on them by...