He served at sea and in the coastal artillery, finishing his service aboard the battlecruiser SMS Hindenburg, and rising to the rank of Leutnant zur see.

[1] On 31 March 1944, Geibel was transferred to the General Government and named the SS and Police Leader (SSPF) in Warsaw, as the permanent replacement to SS-Brigadeführer Franz Kutschera who had been assassinated on 1 February.

As the commander of all the SS and police forces in the city, Geibel was one of the chief participants in the suppression of the uprising, and was involved in the massacre in the Mokotów prison that resulted in the murder of approximately 600 inmates.

Following the defeat of the Polish forces, Geibel played a key role in the retaliatory destruction of Warsaw ordered by Reichsführer-SS Heinrich Himmler.

He left his post as SSPF in Warsaw on 1 February 1945 and was appointed commander of the Ordnungspolizei forces in Prague in the Protectorate of Bohemia-Moravia where he remained until the end of the war in Europe on 8 May 1945.