Kraut

google

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late 18th century (in Kraut (sense 2)): from German, ‘cabbage’; Kraut (sense 1), which was frequently used during the First World War or Second World War, probably alludes to the use of cabbage as an ingredient in dishes considered typical of German cuisine.

wiktionary

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Clipping of  sauerkraut, from German Sauerkraut. Compare German Kraut(“cabbage”). 

kraut (plural krauts)

etymonline

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Kraut (n.)

"a German" (especially a German soldier), 1841, but popularized during World War I, from German kraut "cabbage," considered a characteristic national dish. The "cabbage" sense is attested in English from 1855.