"Tora! Tora! Tora" is a signal to attack...

The tora of the title is the two-syllable Japanese codeword used to indicate that complete surprise had been achieved. It is a coincidence that tora also means "tiger" The attack commenced at 7:48 a.m. Hawaiian Time . The base was attacked by 353 Imperial Japanese aircraft in two waves, launched from six aircraft carriers. All eight U.S. Navy battleships were damaged, with four sunk.