 <unk> Campbeltown for the raid took ten days . She had to be lightened to raise her draught to get over the sand banks in the estuary . This was achieved by completely stripping all her internal compartments . The dockyard removed her three 4 inch ( 100 mm ) guns , torpedoes and depth charges from the deck and replaced the forward gun with a light quick – firing 12 pounder ( 3 " ) . Eight 20 mm <unk> were installed on mountings raised above deck level . The bridge and <unk> were given extra armour @-@ plate protection , and two rows of armour were fixed along the sides of the ship to protect the Commandos on the open deck . 
