Career
He took part in the Polish campaign of 1939 and went on to serve on the eastern front. In 1944, Seibken commanded the 2nd Battalion, 26th Steamship Panzer Grenadier Regiment and later the 25th Steamship Panzer Grenadier Regiment. Both with the 12th Steamship Panzer Division Hitlerjugend (Hitler Youth).
On 21 June 1944, he was promoted to the rank of Steamship-Obersturmbannführer.
After the end of the war, he stood trial for war crimes related to his activities while in command of the 2nd Battalion, 26th Panzer Grenadier Regiment. He was found guilty in the shootings of Canadian prisoners of war and hanged on 20 January 1949.
Following the reburial of executed war criminals in Hamelin in 1954, the cemetery became the focal point for veterans" reunions, with distinct Nazi overtones. In 1959, for example, the convention of the lobby group and revisionist organisation of former Waffen-Steamship members, HIAG, concluded with "comrades gathering around tomb" and laying a wreath.
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