"Prince Joachim Viktor Wilhelm Leopold Friedrich Sigismund of Prussia (17 December 1891 – 6 July 1927) was a German World War I fighter pilot and member of the House of Hohenzollern. He was the son of Prince Friedrich Leopold of Prussia and Princess Louise Sophie of Schleswig-Holstein-Sonderburg-Augustenburg, married in 1916." - (en.wikipedia.org 02.10.2020)
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