https://en.wikipedia.org/wiki/No.10(Inter-Allied)Commando#No._3_Troop(%22X%22_Troop)

No. 3 Troop, perhaps better known as "X" Troop, was possibly the strangest unit in the British Army, since it consisted mostly of personnel who were technically enemy aliens – German and Austrian refugees, many of them Jews – under the command of Captain Bryan Hilton-Jones. The existence of No 3 (X) Troop was first publicly referred to in the 1971 edition of the Alpine Journal in its obituary of Bryan Hilton-Jones.[14] Its first members, in July 1942, were eight Sudeten Germans from Czechoslovakia.[15] Officially named No. 3 (British) Troop as a cover, the name "X Troop" was devised by Winston Churchill; "Because they will be unknown warriors… they must perforce be considered an unknown quantity. Since the algebraic symbol for unknown is X, let us call them X Troop".[16]

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