Less than ninety days after the Japanese Navy attacked Pearl Harbor in December 1941 they launched a second attack on Pearl harbor. The attack would occur on March 4th 1942 and was called K-Operation. It came about because of the confusion and tying up of war materials, men and money created after the Japanese had attacked the oil tank field at Elwood City, California with submarine I-17. This Pearl Harbor attack was designed to put fear in to the American people again and with the clamoring of them for more protection in Pearl Harbor the results would confine American Warships to Pearl harbor for protection instead of having them out on the ocean hunting the Japanese Navy.
The Japanese would use two of their giant four-engine flying boats (Kawanishi H8K"Emily" ) each carrying one ton of bombs (about four bombs). The bombers flew from Japan to Wotje (Marshall Islands) refuel than fly to the French Frigate Shoals, about 500 miles from the Oahu, Hawaiian islands. There submarines I-15, I-19 and I-26, which had been converted to carried aviation gasoline, would refuel them for their bomb attack. The Flying Boats would make one pass at 1 AM drop their bombs and then fly back to Wotje.
All went well until they arrived over Pearl Harbor and found low overcast clouds obscuring any chance to see the target. They took a chance and dropped their bombs based on their best guess where their target was. If nothing else they would let Pearl Harbor know it could be bombed at will. Their guess as to where the target was failed. One load of bombs fell into the sea. The second load of bombs fell to the East of Honolulu. The planes had been picked up by radar and by their radio messages and once again the military did nothing about it. Instead of thinking the Japanese had attacked them the Army accused the Navy of dropping bombs by mistake and the two services argued back and forth for a day or so until bomb fragments were analyzed and it was determined it was Japanese. The two Flying Boats returned safely to Wotje.