The only way to contend with the Japanese who are extremely well trained in close combat is to defeat them at sea before they land. To prove this to his disbelieving officers, Soon-shin puts the three Japanese spies that were captured in Bup-sung in a fighting match with Chung Oon's men. Chung Oon's men are quickly defeated. The shipyard is the busiest place in the base since the training began. One day before the training at sea, the shipyard supervisor Cho Su-chang finds a major structural problem in one of the ships built twenty years ago and reports it to Kim Wan. Kim can't get himself to tell Soon-shin that training has to be canceled, and Su-chang cannot assert himself since the problem was caused by poor maintenance, which is partly his fault. But fearing a disastrous accident at sea, Su-chang goes out to the ship at night and begins destroying the ship.
—https://www.yidio.com/show/the-immortal-yi-soon-shin