After 1918, the term Freikorps was used for the paramilitary organizations that sprang up around the German Empire, including in the Baltic states as soldiers returned in defeat from World War I. It was one of the many Weimar paramilitary groups active during that time.
In 1917 the Russian Bolsheviks ceded the Baltic areas to Germany under the Treaty of Brest-Litovsk. The Imperial German government established occupation governments in Estonia and Latvia and granted independence to a puppet government in Lithuania on March 25, 1918. The German Ober Ost occupation authorities under command of Prince Leopold of Bavaria favored the Baltic Germans, who had been the dominant social, economic, and political class in Courland, Livonia, and Estonia since the 13th century. On March 8 and April 12, 1918 the local Baltic German-dominated Land Council of Courland and the United Land Council of Livonia, Estonia, Riga and Ösel had declared themselves independent states, known as the Duchy of Courland and the Baltic State (Baltischer Staat), respectively. Both states proclaimed themselves to be in personal union with Prussia, although the German government never responded and acknowledged that claim.
The Baltic lands were nominally recognized as a sovereign state by Kaiser Wilhelm II on September 22, 1918, half a year after the newly Soviet Russia had formally relinquished all authority over its former Imperial Baltic provinces in the Treaty of Brest-Litovsk. On November 5, 1918, a temporary Regency Council (Regentschaftsrat) for the United Baltic Duchy, led by Baron Adolf Pilar von Pilchau, was formed on a joint basis from the two local Land Councils.
Under the terms of the November 11, 1918 Armistice the German Army was required to withdraw its troops from all other countries on a timetable established by the Allied Control Commission. As elsewhere, pro-socialist soldiers’ councils controlled many German troop units in the Baltic area, but the Allied Control Commission insisted that the German troops remain to prevent the region be occupied by the Red Army. The Russian Red Army, led by the Latvian Riflemen was making serious inroads into Estonia and Latvia. The Estonians offered tough resistance to the Red Army and refused to ask for, or accept, German Army support. Instead, Scandinavian soldiers from Finland, Sweden, and Denmark came to their support. The Estonians, with this help and naval support from the British, were able to prevail over the Red Army after a year long fight.
Meanwhile the Latvian People's Council (Tautas Padome) proclaimed Latvia's independence from Russia on November 18, 1918. Latvian leader Kārlis Ulmanis requested German Freikorps support for assistance against the Bolsheviks. The British observer, Colonel Sir Hubert Gough, invoked Article 12 of the Armistice Agreement which provided that German troops must evacuate all territories belonging to the Russian Empire, but only "as soon as the Allies shall consider this desirable, having regard to the interior conditions of these territories."
As many of the demoralized German soldiers were being withdrawn from Latvia, Major Bischoff formed a Freikorps unit called the Eiserne Brigade (translated: "Iron Brigade"). This unit was deployed to Riga and used to delay the Red Army advance. Meanwhile, volunteers were recruited from Germany, with promises of land, a chance to fight Bolshevism, and other enticements of dubious veracity. These soldiers, along with remnants of the German 8th Army and the Eiserne Brigade, were reconstituted into the Eiserne (Iron) Division. Also, the Baltic Germans and some Latvians formed the Baltische Landeswehr. The official mission assigned to this force was to prevent any Red Army advance into East Prussia, but its real mission was to help the Baltic Germans re-establish their own state or dominance in Latvia.
Initially, the Iron Division was commanded by General Rüdiger von der Goltz and the Baltische Landeswehr by Major Alfred Fletcher, a German of Scottish ancestry. In late February, only the seaport of Liepaja and surroundings remained in the hands of the German and Latvian forces. In March 1919, General Rüdiger von der Goltz won a series of victories over the Red forces. The main blow in the campaign was delivered by the German Freikorps, which first occupied port of Ventspils and then drove south to Riga. This attack appears to have been coordinated with the Estonians who drove the Bolsheviks from the northern part of Latvia.
The Allies ordered the German government to withdraw its troops from the Baltic after defeat of Bolsheviks. General von der Goltz attempted to seize control of Latvia with the assistance of the local ethnic German population. On April 16 he organised a coup d'état in Liepāja, the provisional national government of Latvia took refuge aboard steamship "Saratow". A new puppet government headed by Pastor Andrievs Niedra was proclaimed. Pastor Niedra was a Latvian Lutheran minister with pro-German sympathies. The Germans convinced the British to postpone the withdrawal of the German Freikorps units because this would give the Bolsheviks a free hand. Britain backed down after recognizing the gravity of the military situation, and the Freikorps moved on and captured Riga on May 23, 1919.
After the capture of Riga, the Freikorps were accused of killing 300 Latvians in Jelgava, 200 in Tukums, 125 in Daugavgrīva, and over 3,000 in Riga. The Latvian nationalists had turned against the German Freikorps and sought assistance from the Estonian troops who had occupied Latvian territory north of the Daugava River. General von der Goltz ordered his troops to advance north towards the Latvian city of Cēsis. The objective of the German forces had now clearly become the establishment of German supremacy in the Baltic by eliminating the Estonian military and Latvian national units, not the defeat of the Bolsheviks. The Estonian commander General Johan Laidoner, insisted the Germans withdraw to a line south of the Gauja river. He also ordered the Estonian army to seize the Gulbene railroad station.
On June 19, 1919, the Iron Division launched an attack to capture Cēsis. Initially, the Freikorps captured the town of Straupe and continued their advance toward Limbaži. The Estonians launched a counterattack and drove the Freikorps out of Limbaži. On June 21, the Estonians received reinforcements and immediately attacked the Landeswehr under Fletcher, who was forced to withdrawn from an area to the northeast of Cēsis. The Iron Division attacked from Straupe towards Stalbe in an effort to relieve pressure on the Landeswehr. On the morning of June 23, the Germans began a general retreat toward Riga.
The Allies again insisted that the Germans withdraw their remaining troops from Latvia, and on June 3 intervened to impose an armistice between the Latvians and Estonians and the Freikorps when the Latvians and Estonians were about to march into Riga. The British insisted that Count von der Goltz leave Latvia. Lieutenant-Colonel Harold Alexander, a British officer, was given command of the Landeswehr which was incorporated in Latvian national army and sent to Eastern Latvia against Bolsheviks. Major Fletcher, its former commander was also ordered out of Latvia.
On September 21 von der Golz turned his troops over to General Bermondt's West Russian Volunteer Army. Major Bischoff created a German Legion from over a dozen Freikorps units and turned these units to General Bermondt. In all, the Germans transferred over 14,000 men, 64 aircraft, 56 artillery pieces, and 156 machine guns. Six cavalry units and a field hospital also went over to Bermondt. Bermondt's offensive was subsequently defeated by the Latvian Army, which received assistance from British and French warships and Estonian armoured trains.
The Freikorps had saved Latvia from capture by the Red Army in the spring of 1919. However, the Freikorps' goal of creating a German dominated state in Courland and Livonia failed. Many of the German Freikorps members who served in the Baltic left Latvia with the belief that they had been "stabbed in the back" by the Weimar Republic under president Friedrich Ebert. Hundreds of Baltic Freikorps soldiers had planned to settle in Latvia, and for those who had fought there, the land made a lasting impression and many of them longed for the day that they could return there. The Baltic Freikorps characterized their struggle against the Reds as the "Ritt gen Osten," (the ride towards the East), and more than one Freikorps unit returned to Germany and planned for the day of the return.
According to historian Robert GL Waite, while retreating from the Baltic, discipline amongst the Freikorps broke down and many fighters "ran wild through the country side marauding in complete disorder" 
"We roared our songs into the air and threw hand grenades after them . . . We saw red. We no longer had anything of human decency left in our hearts. The land where we had lived groaned with destruction. Where once peaceful villages stood, was now only soot, ashes, and burning embers after we had passed. We kindled a funeral pyre and more than dead material burned there - there burned our hopes, our longings; there burned the bürgerlich tablets, the laws and values of the civilized world; there burned everything. . . . And so we came back swaggering, drunken, laden with plunder"