Seydlitz was sister to the Eugeun, Blucher, and Hipper. According to what I've I've read...never completed. I believe she was layed down ?
Perhaps then completed as GZ ?
If so then a "top-notch" CA/CV.
I'll have to take a closer look at both hulls.
I've also read the Russians loaded GZ with "Bootie" and attempted to sail back to Russia. They hit a mine (probably one of their own), and sunk. Tsk-tsk.

Sorry for the guess, totally different ships, lengths Lutzow/sisters 186m, Eugen/sisters 212.5, GZ/proposed sister 262.5
Seydlitz was launched/never completed, sunk in place, scrapped by Russians.

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