In response to the Slovak National Uprising in August 1944, Berger was appointed Military Commander in Slovakia and was in charge during the initial failure to suppress the revolt.

He trained and worked as a physical education teacher, despite his injuries, and lost interest in politics for some years,[5] before rejoining the Nazi Party in 1929,[2] and the paramilitary Sturmabteilung (SA) in January 1931.

He quoted the Commander-in-Chief of the Army, Generaloberst Werner von Fritsch as saying, "If the Reich Transport Minister has his militarily-trained Railway Police, why shouldn't Himmler also play at soldiers?

[19] This rapid transformation was theoretical to a significant extent, as Eicke and the SS-TV continued to resist exchanges of personnel with the SS-VT.[20] The fact that Berger was able to expand the SS combat troops so quickly was a tribute to his improvisational skills.

[33] Berger's recruiting work with the Flemish and Croatian communities was facilitated by his chairmanship of both the Deutsche-Flämischen Studiengruppe (German-Flemish Studies Group) and the Deutsche-Kroatischen Gesellschaft (German-Croatian Society).

[37] The section targeting recruits from outside of the Reich developed out of a briefing he received from the Chief of the SS-Führungshauptamt (SS Command Main Office, or SS-FHA) SS-Brigadeführer Hans Jüttner on Hitler's expectations of the Waffen-SS for the upcoming invasion of the Soviet Union, which included the raising of a fourth division and the expansion of the LSSAH to a motorised brigade.

[40] One of the obvious sources for Waffen-SS manpower was the nearly 40,000 troops of the SS-TV regiments, which consisted of youths below conscription age for the Wehrmacht, as well as older Allgemeine-SS reservists.

[41] In late 1940, in order to ensure that Himmler's instructions were carried out, Berger established a special camp at Sennheim in occupied Alsace, where non-Reich German recruits could be brought up to physical standards and ideologically indoctrinated prior to Waffen-SS training.

[10] In September 1940, Dirlewanger's unit had been deployed to the area of occupied Poland, where they established defensive positions and provided guards for a Jewish labour camp.

[47] In early April 1941, Hitler had agreed to the creation of the SS-Freiwilligenstandarte Nordwest (SS Volunteer Regiment Northwest), with an authorised strength of 2,500 men recruited from Flanders and the Netherlands.

In this, Berger was exploiting Mussert and De Clerq, because he was actually working towards Hitler's idea of incorporating Flanders and Wallonia into the Reich as two Gaue, not a unified autonomous entity.

Himmler decided that there were large numbers of potential pro-German but nationalistic recruits available from the "Germanic" races in occupied countries, and directed Berger to explore this manpower source.

As a result of Himmler's decision, the Wehrmacht was permitted to recruit Frenchmen, Spaniards and Croats, while Dutch, Flemish, Swedish, Norwegian and Danish men were Berger's domain.

[56] Immediately after the lightning-quick defeat of Yugoslavia in April 1941, Hausser was being pressed to accept Yugoslav Volksdeutsche into his renamed SS-Division-Reich, even before it was withdrawn to prepare for Operation Barbarossa.

[32] Not content with this fairly minor and surreptitious recruiting effort, Berger proposed to raise a seventh Waffen-SS division from the ethnic Germans of Yugoslavia.

His recruiters initially struggled to attract volunteers, so coercion was applied, and ultimately, the Banat was declared to be under German sovereignty, and Himmler approved conscription on the basis of an archaic law, the Tiroler Landsturmordnung (Tyrolean General Levy Act) of 1872.

[60] Later that year, when an SS judge issued an arrest warrant for Dirlewanger in response to his unit's anti-partisan operations, the SS-HA chief intervened with Himmler saying, "Better to shoot two Poles too many than one too few.

[68] On 24 November 1942, the Chief of the Gestapo, Heinrich Müller advised Himmler of a proposal he had received from Berger that a Hungarian SS division could be financed by selling emigration permits to Slovak Jews.

According to Stein, Berger had no illusions about the motives of his West European recruits, but paid mere lip service to the idea that they joined the "anti-communist" cause out of idealism.

As a result, the SS-HA issued a series of pamphlets on racial ideology, including Der Untermensch (The Sub-Human), which described certain peoples as spiritually and mentally lower than animals.

[80] In April, losses at Stalingrad and in Tunisia allowed Berger to recruit from foreign workers in the Reich, over the objections of Reichsminister Albert Speer, the Minister for Armaments and War Production.

Not long after the two new volunteer brigades had been formed and committed to battle, they were upgraded to divisional status, and a third Baltic division was authorised, using the manpower of the Latvian security battalions.

[98] At the same time as the Balkan Muslim experiment, divisions were raised from Ukrainian, Russian and Hungarian men, demonstrating that racial exclusivity was no longer an entry requirement for the Waffen-SS.

The first division was handed over to the Russian Liberation Army of Andrey Vlasov before it saw combat, and the second saw action on the Western Front in late 1944 before being reconstituted as a "White Ruthenian" brigade in March 1945.

[110] This followed the failed attempt on Hitler's life earlier that month, when the Führer turned to his "faithful Heinrich" to head the Replacement Army, and the SS chief quickly delegated the responsibility to Berger.

Berger intended to surrender separately to American forces, and after two days delay, managed to locate a regimental commander of the 101st Airborne Division near Berchtesgaden south of Salzburg.

[8] The historian Gerhard Rempel described him as a skilled bureaucratic manipulator, who was "unscrupulous, blunt, and inelegant in manner and expression, yet also full of genial loquacity and racy humour".

Despite the fact that Berger would have preferred a field command, he was one of Himmler's few trusted senior lieutenants, and his recruiting and organisational skills meant he was kept as chief of the SS-HA throughout the war.

The final indictment against Berger and his co-defendants was lodged on 18 November 1947; the trial commenced on 6 January 1948,[134] before Judges William C. Christianson (presiding), Maguire and Leon W. Powers, and ended on 13 April 1949.

[137] During the war, Berger wrote in an article, "We the National Socialists believe the Fuhrer when he says that the annihilation of Jewry in Europe stands at the end of the fight instigated by the Jewish World Parasite against us as his strongest enemy.