An image of the controls, a mere portion of them, as found on a German submarine [UB-110] from that era of the Great War:
"German Submarine, UB-110. Photo of Control room looking aft, starboard side . . . This image shows manhole to periscope wall, valve wheels for flooding and blowing. Han[d]wheels for periscope gear, air pressure gauges."
That degree of complexity at the time was standard? And vital to the submarine diving, surfacing, running level under the water, etc. One little error at station and the whole boat and crew in peril.
A number of crewmen required to operate and UNDERSTAND FULLY WELL that sequence of events that must occur for the vessel to deploy and be effective in a combat environment.
These various controls AGAIN only a small portion [albeit very vital controls] of the whole. Extraordinary complexity even for the most mundane of functions and all being part of a much larger operation mandating teamwork of the most extraordinary order!!
NO ONE EVER SAID ANY OF THIS WAS GOING TO BE EASY!.