Persian Gulf National Day is an official holiday in Iran observed on the 10th day of Ordibehesht, the second month in the Iranian calendar. This usually coincides with 29 or 30 April of the Gregorian calendar. The purpose of this holiday is to celebrate the history, name, and significance of the Persian Gulf. The holiday commemorates the day that combined forces of the Safavid Empire and the British East India Company captured Ormuz expelled the Portuguese from the Strait of Hormuz.