In August 1937, Songhu was under heavy artillery fire. Chen Du, a modern deep-diving engineer, took his mini diving working cabin and plunged into the bottom of the Huangpu River.
He doesn't wear a military uniform, he doesn't have a system mall, he only has a high-pressure chamber that can weld and cut. While other time travelers were busy exchanging weapons for German weapons and killing majors, Chen Du was installing magnetic mines under Japanese warships in the dark, or sneaking into the bombed Jiangnan Shipyard to dig out still usable machine tools from the scrap metal pile.
Relying on his memory of historical shipwrecks, he salvaged steel plates from sunken merchant ships and welded them overnight into an "underwater wolf pack" trap designed to pierce the bottom of Japanese motorboats. He used rudimentary materials to synthesize oxygen and guide circuits, and transformed dumb torpedoes into smart hunting weapons. He listened to Japanese motorboats passing by underwater, hid penicillin in the bridge piers of the concession, and used engineering to turn the mud at the Yangtze River estuary into a tomb for the invaders.
This is a war with no gunfire. While the frontal battlefield was struggling in the "flesh mill", the "He Bo" at the bottom of the river was using wrenches and welding guns to cut off the enemy's supply lifeline bit by bit. Chen Du didn't ask for generals or prime ministerships, he just wanted to be the hardest screw in these bleak years.
