Big ___ , German siege howitzer built by Krupp and used by the German army in WWI (6)

I believe the answer is:

bertha

(Other definitions for bertha that I've seen before include "Girl's name - big German WWI gun" , "Female name; Big -, World War one German howitzer" , "Breath (anag) - girl's name" , "big woman?" , "43-ton German howitzer, Big _____" .)

I've seen this clue in The Guardian.

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