On 7 May 1963, government officials invoked a rarely enforced 1958 law known as Decree Number 10 to prohibit the display of religious flags, forbidding Buddhists from flying their flag on Vesak, the birthday of Gautama Buddha. The application of the law caused indignation among Buddhists in the lead-up to the most important religious festival of the year, as Catholics had been allowed to display Vatican flags a week earlier at a celebration for Diệm's elder brother, Archbishop Ngô Đình Thục. On 8 May, in Huế, a crowd of Buddhists protested against the ban on the Buddhist flag. The police and army broke up the protest by opening fire and throwing grenades at the demonstrators, leaving nine dead.