During the first two years of the Korean War, all US Naval ship losses and 70 percent of our casualties were
directly related to mine warfare. Minesweeping personnel made up only 2 percent of our naval forces in Korea, but
accounted for over 20 percent of our naval casualties.
A minefield is a strategic, rather than tactical, weapon. A field is generally seeded with a variety of devices.
The most primitive explode on contact or detonate magnetically when they pick up the magnetic field of a passing
Clearing lanes required the sweepers to sail in straight lines, which made them extremely vulnerable to fire from shore batteries such
as those on Sin-Do.
Russian technicians and advisers had provided, planned the fields, and
supervised the laying of least 2,000 mines of all types - contact inertia, contact chemical, pressure, and electronic.
Civilians impressed from Wonsan had laid the mines by rolling them off towed barges. The Russians had meant
to lay 4,000 mines, but had not finished when the ROKs drove them out of Wonsan.
The method of clearing these fields was to use minesweepers towing paravanes, a torpedo-shaped float similar in shape to a Harvey Torpedo, which is pulled away from the ship towing it, moored mines being snagged and deflected away from the ship towards the paravane by the towing wire, where it is exploded, or sunk, by cannon fire.
Minesweeping paravane on HMAS MILDURA, August 1951