Polish history begins in AD 966 when Misezko I began writing it's history. Beforehand Poland did not exist, but was occupied by the Polanie, Wislanie, Pomorzanie and Mazovian Slavic tribes. All other Slavic tribes were incorporated into German expansion, or the Czech state.
In AD 1000, the Polish church was established with agreement from Otto III, Holy Roman Emperor, and could now turn to the Pope for protection. And would not fall under German influence.
AD 1024, saw the Coronation of Boleslaw I Chrobry which created Poland as an official independant kingdom.
Now, skipping a few hundred years, to the 18th Century. After years of war the Polish Republic (Poland and Lituania) was weak. It only had a 24,000 man army, and had three great enemies on it's borders. Russia, Prussia and Austria were all poised to invade.
Russia used military pressure from it's 330,000 strong army to influence the Republic, which first occured in 1768 when the 'Cardinal Rights' were forced upon the Republic.
Catherine II split the Republic in 1772 with Austria and Prussia. The Republic took advantage of a war between Russia and Turkey to reform it's forces and build an army of 100,000 men. They also wrote up Europe's first constitution which did not go down well in Russia, so Russia invaded in 1792 which ended in the Republic's defeat. What was left of the Republic after the first partition now became a Russian protectorate. Poland was now under the control of Austria, Prussia and Russia completely.
In 1794, Poland broke out in rebellion and Warsaw, Krakow and Wilno were liberated. But a combined Prussian and Russian assault reconquered all the lands. In 1795 the three powers once again moved deeper into Poland, and calved the state completely. Poland was effectively destroyed, and was wiped off the European map. Prussia controlled Warsaw and lands up to Niemen River.
Napoleon then burst on to the European scene, and Poland were quick to become his allies. In 1797 Polish legions were set up in Italy, and helped Napoleon defeat Austria, Prussia and Russia in 1806-1807. The Prussian-annexed parts of Poland became the new Poland under the Duchy of Warsaw, and a Polish government was formed under Napoleonic influence.
Napoleon then attempted on Russia in 1812. His failure there brought Poland back on the brink of devestation. This was brought about in 1813 when Napoleon was defeated at Leipzig in 1813. The Congress of Vienna in 1815 then handed some of the preowned lands in Poland back to Prussia. The remaining lands became the Kingdom of Poland, attached to Russia. Tsar Alexander I was the king.
In 1830, Poland uprose and dethroned the Tsar. They held out against Russia until 1831 when the massive Russian army defeated them. This led to slaughter of thousands of Poles, and the closure of all that was Polish. Many Poles went into exile, mostly in France.
Austria and Prussia then began reform in their Polish held lands, handing much land over to the peasants. Bringing those areas into the new age. But in the Russian zone it remained much the same, and Poland was oppressed by the large nation. Many revolts and uprisings followed, but all were crushed.
During World War I, Poland decided to ally itself with Germany and Austro-Hungary against Russia. Come 1915, Austro-Hungary and Germany had pushed Russia out of all of Poland. And many local governments were set-up in these lands.
Poland then refused to fight for the Central Powers against the West. When Russia pulled out the war, the Western Powers sought to create a more powerful Poland and came to their aid. An amazing stroke of luck for Poland saw all three controlling powers (Russia, Germany [Prussia] and Austria) defeated.
The Treaty of Versailles then struggled to recreate Poland's borders before the paritition. And this led to many disputes. Poland was handed lands that were not hers, Russia took lands, and the Czechs were not happy. Poland was handed Pomerania, but Gdansk (Danzig) was kept a free city under the League of Nations. Upper Silesia was handed over after many Polish uprisings, but East Prussia and the rest of Upper Silesia remained in 'Polish' terrority. The biggest problem remained in Ukraine which was under Polish control before the partition but Russia believed was hers. And Ukraine wanted to be independant.
But, in any case, the only lands Germany wanted back was Pomerania, Danzig and Upper Silesia. This mainly was known as the 'Polish Corridor' which was what the whole dispute was about. I'm sure some of that is wrong, but that's all I can remember! I had to argue with a Polak once about his own history... Well, alright some of the information I dug in my books for.