The plan wasn't to conquer America. They planned to take over South East asia with the lovely oil and raw materials which Japan didn't have on their island or Manchuria. If they invaded the US would intervene so they planned to destroy the whole of the American fleet so they could invade and America would have to surrender (or the Japanese could fortify their positions when the Americans had rebuilt).

The japanese didn't destroy the Carriers and didn't destroy the fuel depots at Pearl Harbour, as well as the Americans rebuilding the fleet faster than they thought they could.