SD Gundam Sangokuden: Fuuun Gouketsu-hen

It was the times of war in the continent of Mirisha, a time where the three kingdoms of Shou, Gou and Giga struggle for power and authority. Before the three countries become established, the rebellion of the Yellow Scarves has allowed Toutaku to seize control over the government, he killed Reitei the emperor of that time and stole the "Gyokuji," then promoted himself to Prime Minister spreading tyranny through the land. But a year after, the anti-Toutaku spirits are on the rise because of the discovery of Reitei's assassination, Enshuu was quick on gathering troops and with Sousou on board the anti-Toutaku alliance is formed. Heroes from all over gather under the anti-Toutaku banner, including Ryuubi's Yuushu Resistance. The anti-Toutaku allied forces fought against the Toutaku Troops at the Korou Fortress which is just outside Rakuyou.

(Source: Gundam Wikia)