He wrote the poem onboard the battleship Nagato, his flagship as commander in chief Combined Fleet. So the rising sun would have been the ship's pennant. The land of the dawn, of course, was Japan: The two characters Ni-hon (usually pronounced Nippon) mean Sun Source, or the Land Where the Sun Rises. Yamamoto, if we may translate a subtle 31-syllable Japanese poem into blunt English words, was on top of the heap.
It would be foolish to imagine that he did not enjoy his eminence, even as he saw the looming threat of getting into a war with the wrong enemy. He enjoyed a battle, and might even have found a losing battle more interesting. He might have quite liked the idea of being at the center of a big story, and what could be a bigger story than working the miracle of saving Japan from the doom he himself had predicted? After all, going ahead with the attack wasn't his idea. He wasn't that crazy. He had, however, planned an excellent attack.
Or it would have been excellent, if it had caught the American aircraft carriers in harbor. When the returning aircraft reported that the American carriers had not been present, Yamamoto, supervising the operation at long range from the Nagato anchored at Hashirajima in the Inland Sea, knew straight away that the Americans had the wherewithal to go on fighting.
In May 1942, only five months after Pearl Harbor, the American carriers fought him to a draw at the battle of the Coral Sea. At Midway, scarcely more than six months after Pearl Harbor, they destroyed him. He had been right about making things tough for the Americans for six months. Six months of supremacy were all that the Japanese enjoyed. After Midway, they had no chance of keeping the initiative. But we make a mistake if we think they were crazy not to admit defeat. There was always the possibility that they could bring their opponents to terms by making it too costly to go on fighting. Because Yamamoto died early, and because the English-speaking gambler is such a sympathetic character, he tends to be enrolled in the ranks of those who would have seen reason and sought a sane way out. For those who hold that view, a close study of Yamamoto's face can be recommended. He knows your country well, admires its virtues, and doesn't even think he can prevail: But he wants to fight anyway.
People of a literary bent tend to idealize the poet warriors, of whom, in modern times, Yamamoto must count as the most conspicuous, apart from General Patton. But we need to ask ourselves whether a flair for the poetic might not be a limitation to generalship, in which a considered appreciation for the mundane is essential. A poetic flair has an impatient mind of its own: It likes to make an effect, and it has a propensity for two qualities that can easily be inimical to a broad strategic aim. One of those qualities is what A. Alvarez called the shaping spirit, and the other is what Frank Kermode called the sense of an ending. Yamamoto's plan for deciding the war on the first day was not only the equivalent of a roulette player's betting his whole bundle on a single number, it was also the equivalent of trying to cram the whole of The Tale of Genji into a single haiku. There was bound to be material that didn't fit. Even if the American aircraft carriers had been in harbor, they would not have sunk far enough in the shallow water to be beyond salvage. One way or another, the American fleet was bound to come back.
Spiritually, Yamamoto died at Midway. In the matter of his physical death, however, it seems unlikely that he committed suicide in expiation. Romantic interpreters sometimes favor the appealing notion that Yamamoto invited the American ambush that resulted in his being shot down into the jungle of Bougainville on April 18, 1943. But when the Japanese search party tracked down his corpse in the jungle, he was still strapped into his seat. His sword was beside him. If he had wanted to commit suicide, he would probably have done so on dry land or on the deck of a ship, included the sword in the ceremony, and written a poem first.