Vashti was a queen of the Persian Empire and spouse of King Xerxes. Very little is known about her other than what is described in the Book of Esther. As queen she was the king's spouse and of higher esteem than any (potential) concubines. Yet, she had little to no legal authority other than within the palace itself.
Once at a drunken party, Xerxes summoned Vashti to show herself to his government officials, so that they would behold her beauty. She refused the king's command and upon her refusal, Xerxes enacted a law dethroning her and prohibiting her from being a part of the royal court. The fear was that Vashti's behavior would inspire other women of the empire to act rebelliously towards their husbands.
The Feasts of the King
During the third year of her husband's reign, he held a banquet for the highest government officials in the palace. While Xerxes held the banquet for the government officials, Vashti hosted a banquet for the women who lived and worked in the royal palace.
Refusal of Display
During one of the parties of the Xerxes's feast, he became drunk and so commanded the group of seven eunuchs who attended Vashti to bring her to him. The king asked this so that Vashti, wearing her royal crown, could come before him and his partygoers (the government officials) to show her beauty so that they make look at her. Vashti knowing the intention was for the enjoyment and enticement of her spouse and his advisors, she refused when the eunuchs came to bring notify her.
The king infuriated at his trophy wife's refusal to display herself, consulted his closest advisors on the matter. The question was presented of what should be done with the Queen according to the Persian custom. Vashti being a woman, was considered inferior and subject to her husband without question (most prominently with Vashti in matters concerning physical enjoyment), concern arose that her refusal to her husband would arise rebellion of wives in their households. Apparently, Vashti had not only "wronged" her own husband, but the authority of every husband throughout Persia.
It was then recommended that Vashti never be allowed to be in the King's presence again, and a replacement that was "better" (more attractive or more physically pleasing) was to be found, this being irrevocable. This was agreed upon and Vashti was dethroned from the palace. Vashti was likely deposed, being reduced to the life of a commoner, perhaps being banned from the city of Susa so should would never encounter the king.
After Vashti was expelled messengers declared locally the insolence of Vashti against her husband and that every husband would retain rulership over his household. Xerxes retained his anger for some, soon forgetting about Vashti and the comfort she provided. After Xerxes's anger had subsided, he remembered the disobedience and the expulsion of Vashti and missed her physical comfort and attractiveness. To appease Xerxes need for physical satisfaction the king's aide proposed that a pool of replacement virgin candidates be brought in to succeed Vashti and her position.