The commander was the captain of his vessel and responsible for his vessel and his crew. He was in charge of controlling and navigating the vessel at sea. Due to the demanding nature of the job, submarine commanders retired at the age of 40. 

The commander of the submarine led the action from the conning tower during the attacks. At his disposal, he had an attack periscope and the same command equipment as in the command centre: a compass, engine revolution counters, depth gauges and inclinometers, and engine order telegraph. In the conning tower, the commander could fire a torpedo by pressing a launch button. 

The commander used a speaking trumpet to communicate with the command centre, the torpedo room and the engine room. The trumpets still work. You can try using the trumpet for communicating with the command centre and the engine room. The trumpet is on the left hand side of the doorway.