The Japanese attempted to deny the Russians use of Port Arthur. During the night of 13–14 February, the Japanese attempted to block the entrance to Port Arthur by sinking several concrete-filled steamers in the deep water channel to the port, but they sank too deep to be effective. A similar attempt to block the harbour entrance during the night of 3–4 May also failed. In March, the charismatic Vice Admiral Makarov had taken command of the First Russian Pacific Squadron with the intention of breaking out of the Port Arthur blockade.