How useful would large numbers of German Type 27 midget submarines have been if they were available by 1940?
Short answerThey would be localized defensive weapons rather than campaign-changing boats, but their quiet hulls could accelerate anti-submarine detection work such as towed arrays.
NotesThe Type 27 would be a short-range asset that could disrupt amphibious operations, work behind minefields, and matter in constrained waters such as the central Mediterranean. Its speed, range, and support burden limit strategic mobility once the boats arrive by rail. A larger quiet-midget-submarine threat might also push navies to develop better anti-submarine detection earlier, including towed-array approaches.