He joined the Independent Social Democratic Party of Germany (USPD) and took part in March 1920 in the fighting in the wake of the Kapp Putsch on the side of the Ruhr Red Army, in which he served as a section commander.

[4]: 247 He acquired medical knowledge through self-study on organised patient care and also himself led operations by, for example, to ill-treatment by the SS to save the lives of injured inmates or those affected by frozen limbs.

[6] His widow Elisabeth ("Liesel") Kraemer, born Lehmann, received from the camp administration an urn containing his ashes, which was buried in November 1941 in Siegen.

The investigation also led to the arrest of Hauptscharführer Johann Blank, a Buchenwald guard who played a leading role in the actual murder of Kraemer and Peix.

The journalist and political scientist Eugen Kogon (CDU) praised his Buchenwald inmate in 1946's "The SS State" as a "strong, bold personality.

"[9] The East German writer and fellow inmate Bruno Apitz included him in "Naked Among Wolves" (1956, film 1963) by giving the main character the name of Walter Krämer.

[10]: 227  At the Martin Luther University Halle, doctorate Christine Wenzel wrote a dissertation on "The Life and Work of the German Communist Walter Krämer".

[10]: 235 In West Germany, Kraemer was largely unknown outside his region of origin, where his biography was controversially received and he remained without honor for a long time.

On what would have been his 110th birthday in 2002, a memorial stone was erected in Goslar Hahndorf on the initiative of the association "Spurensuche Harzregion" (Harz Region Traces) for the former concentration camp subcamp, in which Kraemer was murdered.

Among those speaking were Karl Prümm, a media scientist who was temporarily active in Siegen, and Romani Rose, Chairman of the Central Council of German Sinti and Roma.

[10]: 232 Since the end of Nazism, an annual wreath-laying ceremony on the second Sunday in September, the "Day of the Victims of Fascism", is held at Kraemer's grave in Siegen.

In the political climate of the Cold War, the Communist Party had little influence in Siegen,[18] unlike in the neighboring district of Altenkirchen, where a convalescent home was named after Kraemer in 1948.

In 1975, the Jewish chairman of the Society for Christian-Jewish Cooperation, Hugo Herrmann, publicly referred to Kraemer, who, he said, had tried in Buchenwald to "put an end to the torture of the Jews", an effort for which he paid with his life.

In November 1979, the VVN submitted a motion to the city's cultural committee to rename the street named after the anti-Semite Adolf Stoecker after Kraemer.

There was a wave of such new street namings in the 1960s and 1970s, for example after Friedrich Flick, Lothar Irle, Jakob Henrich, Ernst Bach, Bernhard Weiss and others.

The Siegen literary scholar Karl Prümm and Klaus Dietermann of the Society for Christian-Jewish Cooperation put forward a proposal to publish a biography of Kraemer in 1986.

Violent opposition to the publication was led by the local CDU politician Paul Tigges (Lennestadt) founder and board member of the Christine Koch company .

The concern for others prevails over the care of the self" At the opening ceremony December 2014, said district administrator Andreas Müller (SPD) of a "dignified event and a momentous day for victories", to which it had been "a long way" since Kraemer have one of the "under wanted Nazi victims".

Mayor Steffen Mues (CDU) declared, Kraemer showed exemplary humanitarian commitment and the resistance against the Nazi regime was more important than the criticism.