Here is some info about the Freikorps and the German-Polish dispute:
In Upper Silesia, one of the wealthiest industrial regions of Germany, the Poles made three military efforts to incorporate the region into their country. These efforts are known as the Polish Uprisings. The first Polish attempt occurred in February 1919 when Polish Nationalists lead by Wojciech Korfanty, a former member of the Reichstag, launched an armed attack to annex Upper Silesia into Poland. The local German population supported the Freikorps units which were successful in stemming the Polish advance. The Freikorps then counterattacked and re-occupied much of Upper Silesia.
On August 17, 1919, about 2:00 A.M., the First Polish Uprising was launched. Korfanty was able to put approximately 22000 insurgents in the field. The POW had initial successes in seizing some warehouses where artillery shells were stored. In less than a day, the German local defense forces were able to check the POW advance. On August 18, Freikorps reinforcements arrived, including the Erhardt Brigade and 3. Marine-Brigade von Lowenfeld. Other Freikorps units also arrived, and these were organized under the command of General Karl Höfer. Heavy skirmishes occurred between the Freikorps and the POW on August 18 and 19. Fighting continued until August 25 with the Freikorps gaining the upper hand and forcing the Poles back to the lines previously established by the Allies.
On the evening of August 17, 1920, Korfanty staged the Second Polish Uprising. In all over three hundred German civilians were killed. This Polish revolt also failed to accomplish its objectives because the local German defense organizations put up a stiff resistance. The Korfanty insurgents pulled back to the original demarcation line, and the Second Polish Uprising ended with the same areas of control between the two parties.
On March 17, 1921, the plebiscite was held. All of the major cities, a majority of Upper Silesian counties and 60% of the voters had opted to remain as part of Germany. Korfanty immediately mobilized the POW, and on May 3, his forces seized control of the cities of Pless, Ryback, and Formowitz. By May 6, Korfanty's forces had captured the eastern two-thirds of Silesia.
German Freikorps units came from all over Germany. FK Oberland came from Upper Bavaria and Austria and was to play a significant role in the recapture of a large part of Upper Silesia. As more and more Freikorps members infiltrated into Upper Silesia dressed as civilians, a plan was developed by the Freikorps leadership to launch a German counterattack.
Now, time to talk about the fascinating Battle of Annaberg. General Bernhard von Hülsen, who had assumed command of the German Freikorps, determined that the German forces should launch a counterattack. General von Hülsen selected as his primary objective the Annaberg monastery because it dominated the plains on the east side of the Oder River and had major symbolic importance because it was the shrine of St. Anne, the patron saint of the German Silesians. Von Hülsen ordered the deployment of seven Freikorps battalions across the Oder River during the late evening of May 20. These troops were ordered to storm the Annaberg and dislodge the POW forces positioned there.
The attacking forces were divided into two detachments: Horadam on the left and to the north of Annaberg; Chappuis on the right and to the southwest. In the misty twilight of May 21, the Freikorps attack the Polish forces on the summit of Annaberg. The Polish defenders were initially caught by surprise. Freikorps Oberland's soldiers charged to the crest of the Annaberg. There was a short period of hand-to-hand combat and then the Poles withdrew down the hill. Several times the Poles counterattacked, but were repulsed. The German drive continued into the city of Annaberg, and its marketplace was secured by 11:30 A.M. The Freikorps continued their advance, and the German forces opened their bridgehead on the east bank of the Oder River to a depth of 25 km. The Poles suffered heavy losses. On June 10 the cease fire was reinstated. The German Freikorps recaptured not only the area around Annaberg , but also recaptured Rosenberg and relieved the pressure on Kattowitz.
The Freikorps had reached its military zenith with the storming of the Annaberg. In 1938, a monument was dedicated to the Freikorps' dead and the bodies of fifty Freikorps fighters were interned there. The monument was desecrated by the Poles after World War II, but the amphitheater built at the same time is still intact. Interestingly, the Freikorps Oberland Veterans Association commemorates May 21 of every year because of its role in the victory at Annaberg. Likewise, the Silesian Poles also have a holiday on May 21 and have erected a museum on the path to the top of the Annaberg which commemorates the three Polish Uprisings. The Storming of Annaberg is a living myth to both the German Freikorps survivors and their descendants and to the Polish insurgents.