January 1920, the corridor was established as Poland's access to the Baltic Sea from 70% of the dissolved province of West Prussia, consisting of a small part of Pomerania with around 140 km of coastline including the Hel Peninsula, and 69 km without it. The primarily German-speaking seaport of Danzig (Gdańsk), controlling the estuary of the main Polish waterway, the Vistula river, became the Free City of Danzig and was placed under the protection of the League of Nations without a plebiscite. After the dock workers of Danzig harbour went on strike during the Polish–Soviet War, refusing to unload ammunition, the Polish Government decided to build an ammunition depot at Westerplatte, and a seaport at Gdynia in the territory of the Corridor, connected to the Upper Silesian industrial centers by the newly constructed Polish Coal Trunk Line railways. Exodus of the German population The German author Christian Raitz von Frentz writes that after First World War ended, the Polish government tried to reverse the systematic Germanization from former decades. Frederick the Great (King in/of Prussia from 1740 to 1786) settled around 300,000 colonists in the eastern provinces of Prussia and aimed at a removal of the Polish nobility, which he treated with contempt. Frederick also described Poles as "slovenly Polish trash" and compared them to the Iroquois. On the other hand, he encouraged administrators and teachers who could speak both German and Polish. Prussia pursued a second colonization aimed at Germanisation after 1832. The Prussians passed laws aiming at Germanisation of the provinces of Posen and West Prussia in the late 19th century. The Prussian Settlement Commission established a further 154,000 colonists, including locals, in the provinces of Posen and West Prussia before World War I. Military personnel were included in the population census. A number of German civil servants and merchants were introduced to the area, which influenced the population status. According to Richard Blanke, 421,029 Germans lived in the area in 1910, making up 42.5% of the population. Blanke has been criticised by Christian Raitz von Frentz, who has classified his book as part of a series on the subject that has an anti-Polish bias; additionally Polish professor A. Cienciala has described Blanke's views as sympathetic to Germany. In addition to the military personnel included in the population census, a number of German civil-servants and merchants were introduced to the area, which influenced the population mix, according to