Mulan

After the Huns, led by the ruthless Shan Yu, invade Han China, the Chinese emperor orders a general mobilization. Conscription notices require one man from each family to join the Chinese army. When Fa Mulan hears that her elderly father Fa Zhou, the only man in their family and an army veteran, is once more to go to war, she becomes anxious and apprehensive. Taking her father's old armor she disguises herself as a man so that she can enlist instead of her parent. The anxious family quickly learn of her departure and Grandmother Fa prays to the family ancestors for Mulan's safety. The ancestors then order their "Great Stone Dragon" to protect Mulan. The ancestors are unaware that the statue of Great Stone Dragon failed to come to life, and that Mushu, a small dragon, is the one sent to protect Mulan.
Reporting to the training camp Mulan is able to pass as a man, although her military skills are initially poor. Mushu provides clumsy guidance in how to behave as a man. Under the command of Captain Li Shang, she and her fellow recruits Yao, Ling and Chien-Po, gradually become trained warriors. Mushu, desiring to see Mulan succeed, creates a fake order from Shang's father, General Li, ordering Shang to follow the main Imperial Army into the mountains. The reinforcements set out but arrive at a burnt-out encampment and discover that General Li and his troops have been massacred by the Huns. As they solemnly leave the mountains, they are ambushed by the Huns, but Mulan cleverly uses a cannon to create an avalanche which buries most of the invaders. An enraged Shan Yu slashes her in the chest, and her deception is revealed when the wound is bandaged. Instead of executing Mulan as the law requires, Shang spare her life, but dismisses her from the army. Mulan is left to follow alone as the recruits depart for the Imperial City to report the news of the Huns' destruction. However it is revealed that several Hun warriors including Shan Yu have survived the avalanche, and Mulan catches sight of them as they make their way to the City, intent on capturing the Emperor.
At the Imperial City, Mulan is unable to convince Shang about Shan Yu's intentions. The Huns capture the Emperor, then seize the palace. With Mulan's help, Yao, Ling, and Chien-Po pose as concubines and are able to enter the palace. With the help of Shang, they defeat Shan Yu's men. As Shang prevents Shan Yu from assassinating the Emperor, Mulan lures the Hun leader onto the roof where she engages him in solo combat. Meanwhile, acting on Mulan's instructions and signal Mushu fires a bundle of fireworks rockets at Shan Yu. The fireworks strike Shan Yu and explode, killing him. Mulan is praised by the Emperor and the assembled inhabitants of the city, who bow to her in an unprecedented honor. While she accepts the Emperor's crest and Shan Yu's sword as gifts, she politely declines his offer to be his advisor and asks to return to her family. She returns home and presents these gifts to her father, but he is more overjoyed to have Mulan back safely. Having become enamored with Mulan, Shang soon arrives under the pretext of returning her helmet, but accepts the family's invitation to stay for dinner. Mushu is granted a position as a Fa family guardian by the ancestors amid a returning celebration.

Question: Who seize the palace?
Answer: the Huns