Jamieson, Fausset and Brown on Esther 1:10-12

10-12. On the seventh day, when the heart of the king was merry with wine--As the feast days advanced, the drinking was more freely indulged in, so that the close was usually marked by great excesses of revelry.

he commanded ... the seven chamberlains--These were the eunuchs who had charge of the royal harem. The refusal of Vashti to obey an order which required her to make an indecent exposure of herself before a company of drunken revellers, was becoming both the modesty of her sex and her rank as queen; for, according to Persian customs, the queen, even more than the wives of other men, was secluded from the public gaze. Had not the king's blood been heated with wine, or his reason overpowered by force of offended pride, he would have perceived that his own honor, as well as hers, was consulted by her dignified conduct.