Laughing out loud, the two men crumpled the sheets of paper and put them in their sleeves.
"Man's wisdom obviously doesn't exceed certain limits," Hideyoshi said.
"That's true," Kanbei agreed. "Takamatsu Castle stands on a plain conveniently surrounded by mountains. Not only that, but the Ashimori and seven other rivers run through the plain. It should not be difficult to divert the water of these rivers and flood the castle. It's a bold plan that most generals would not even think of. I can't help but admire how quickly you grasped the situation, my lord. But why do you hesitate to put it into action?"
"Well, since ancient times, there have been plenty of examples of successful attacks on castles using fire, but almost none with water."
"I think I've seen it mentioned in the military chronicles of the Later Han Dynasty and the period of the Three Kingdoms. In one of the chronicles I read something about our own country during the reign of Emperor Tenchi. When the Chinese invaded, our soldiers built dikes to store water. When the Chinese attacked, the Japanese soldiers were going to cut through the dikes and wash them all away."
"Yes, but they didn't actually have to put the plan into operation because the Chinese withdrew. If this plan is carried out, I'll be using a strategy that has no precedent. So I'm going to have to order some officials who have detailed knowledge of geography to determine what will be necessary in terms of time, expenses, and men for the engineering work."
What Hideyoshi wanted was not just a rough estimate, but concrete figures and a flawless plan.
"Absolutely. One of my retainers is very clever with such things, and if you order him to come here now, I think he'll have a clear answer for you right away. In fact, the strategy I had in mind is based on this man's ideas."
"Who is he?" Hideyoshi asked.
"Yoshida Rokuro," Kanbei replied.
"Well, call him right away." Then Hideyoshi added, "I also have someone at hand who is conversant with construction and land conditions. What would you think about calling him here at the same time and having him talk with Rokuro?"
"That would be good. Who is he?"
"He's not one of my retainers but a samurai from Bitchu. He's called Senbara Kyuemon. He's here in camp right now, and I have him working exclusively on making charts of the area."
Hideyoshi clapped his hands to summon a page, but all of his personal attendants and pages had withdrawn to some distance, and the sound of his clapping did not reach them. The din of the rain compounded the problem. Hideyoshi got up and stepped into next room himself, and yelled out in a voice that would have been more proper on a battlefield, "Hey! Isn't anybody here?"
Once the decision had been taken to proceed with the water attack, the main camp on Mount Ryuo was found to be inconvenient. On the seventh day of the Fifth Month, Hideyoshi moved to Mount Ishii, which had been chosen because it overlooked Takamatsu Castle.
On the following day Hideyoshi said, "Let's start to measure the distances."
Hideyoshi, accompanied by half-a-dozen generals, rode to the west of Takamatsu Castle, to Monzen, on the banks of the Ashimori River. All the while he kept an eye on the castle to his right. Wiping the sweat from his face, Hideyoshi summoned Kyuemon. "What's the distance from the ridge of Mount Ishii to Monzen?" he asked.
"Under a league, my lord," Kyuemon answered.
"Lend me your map."
Taking the map from Kyuemon, Hideyoshi compared the construction of the proposed dike to the lay of the land. There were mountains on three sides, creating a natural baylike formation, extending in the west from Kibi to the mountainous area of the upper reaches of the Ashimori River; in the north from Mount Ryuo to the mountains along the border of Okayama; in the east to the edge of Mount Ishii and Kawazugahana. Takamatsu Castle was situated right in the middle of this open plain.
In Hideyoshi's eyes the fields, rice paddies, riding grounds, and villages on this flat plain were already submerged. The way he saw it, the mountainous banks on three sides could be viewed as a winding line of capes and beaches and Takamatsu Castle itself as a solitary man-made island.
Hideyoshi gave the map back to Kyuemon, reassured about the feasibility of the project, and once again mounted his horse. "Let's go!" he called out to his attendants, then said to Rokuro and Kyuemon, "I'm going to ride from here to Mount Ishii. Take the measurements for the dike by following the hoofmarks of my horse."
Hideyoshi turned his horse due east and galloped off, riding straight from Monzen to Harakozai, and then describing an arc from there to Mount Ishii. Kyuemon and Rokuro chased behind him, leaving a trail of powdered rice meal. After them followed laborers who drove in stakes to mark the line of the dike.
When the line that had been drawn became an embankment and the waters of the seven rivers were diverted to flow inside it, the entire area would become a huge lake shaped like a half-open lotus leaf. When the men looked carefully at the lay of the land that formed the border between Bizen and Bitchu, they realized that it must have been part of the sea in the distant past. The battle had commenced. It was not to be a battle of blood, but a war waged against the earth.
The length of the dike was to be one league; its width was to be thirty feet at the top and sixty feet at the base. The problem was its height, which had to be proportional to the height of the walls of Takamatsu Castle.
In fact, the primary factor assuring the success of the water attack was the fact that the castle's outer stone walls were only twelve feet high. Thus the height of the dike of twenty-four feet was figured from a base of twelve feet. It was calculated that if the water level rose to that height, it would not only submerge the castle's outer stone walls but also flood the castle itself under six feet of water.
It is only rarely, however, that a project is completed ahead of schedule. And the problem that so troubled Kanbei was one of human resources. For the most part, he would have to rely on the local farmers. The population of the neighboring villages, however, was rather sparse, because Muneharu had taken more than five hundred farming families into the castle before the siege, and many others had fled to the mountains.
The farmers who had taken refuge in the castle were ready to live or die with their lord. They were good, simple folk who had served Muneharu for years. Many of those who remained in the villages were people of bad character, or opportunists who were willing to work on a battlefield.
Hideyoshi could count on the cooperation of Ukita Naoie, and Kanbei was able to muster several thousand men from Okayama. But what troubled him was not getting this number of men together; his problem was how to use those human resources with the greatest efficiency.
On a tour of inspection, he called over Rokuro and asked for a progress report.
"I'm sorry to say that we may not meet His Lordship's schedule," Rokuro replied sadly.
Even the mathematical brain of this man could not figure out how to extract hard rk from the mixed group of laborers and ruffians. For this reason a series of guardhouses had been set up every ninety yards along the dike, and soldiers were stationed at each of these surveillance points to encourage the laborers. Because the soldiers were simply there as passive observers, however, the thousands of men who swung their mattocks and shouldered dirt like ants were hardly spurred on at all.
Moreover, the timetable that Hideyoshi had imposed was extremely tight. Urgent messages reached him night and day. The forty thousand troops of the Mori had split into three armies under Kikkawa, Kobayakawa, and Terumoto, and they were getting closer to the provincial border by the hour.