The Attack
At the Yamato encampment: The 1,600 soldiers were eating their poor meals: two riceballs and some water. The generals however, were eating roasted boar, white rice, fish, and drank expensive Sake. General Konishi: " My lord." Lord Tachi: " Yes?" Konishi: " Yukisu and Niu have joined forces." " I am aware, Konishi, but still, we still have more troops." "But the enemy troops are being well fed." " Fool, that is because their province has more Koku than ours'." " But, that means their morale will be greater than our's." " Quiet, you fool!" " But…." " That's enough, Konishi." " Tell the troops to build their tents." "Yes"
The next day: " Organize the soldiers." " Yes" " Today, we attack Yukisu and Niu." The soldiers held their Yari {spears} and banners up. The main banners were: Tachi's, White with characters that read "Bear of Yamato"; Konishi's were Red with his family name engraved in Black; And Kurogane's were Yellow with the Ichimonji clan's crest engraved on it { like Hidetora's} Niu had black banners with his province's name on it. Yukisu's was Green with his name on it. Tachi had split half his forces into two groups of 400 men. He kept the full half. Konishi and Kurogane each took 400 men.
The Battle of Hunjo no Kira
Tachi had his Archers firing behind his Spearmen. His spearmen's charge almost wiped out Yukisu's cavalry. Then something caught Kurogane's attention. He saw that Niu's force was almost completely Ashigaru. They were armed with short spears. When Tachi was told, he laughed, and sent 1,000 men to obliterate the enemy. After a short time of fighting, 450 out of the 600 Ashigaru under Niu were killed. Niu then fled into a nearby forest with his 350 men. Ignoring his advisers, Tachi sent 500 cavalrymen after Niu. He wanted to kill Niu. When Tachi's men got into the forest, they were ambushed. 300 spearmen came from each side of the woods. All of those 500 cavalrymen were killed. Tachi retreated back to Yamato.
The reason Tachi didn't think the enemy had more soldiers on the field was because he was misinformed. He was told Niu had 800 men, when Niu really had 1,400 men.