The Observance of 5th November Act 1605 (3 Ja. I, c. 1,) also known as the "Thanksgiving Act", was an Act of the Parliament of England passed in 1606 in the aftermath of the Gunpowder Plot.
The Bill was drafted and introduced on 23 January 1605/06 by Edward Montagu. It called for a public, annual thanksgiving for the failure of the Plot.
Forasmuch as almighty God hath in all ages showed his power and mercy in the miraculous and gracious deliverance of his church, and in the protection of religious kings and states, and that no nation of the earth hath been blessed with greater benefit than this kingdom now enjoyeth, having the same true and free profession of the gospel under our most gracious sovereign lord King James, the most great learned and religious king that ever reigned therein, enriched with a most helpful and plentiful progeny proceeding out of his royal loins promising continuance of this happiness and profession to all posterity: the which many malignant and devilish papists, Jesuits, and seminary priests much envying and fearing, conspired most horribly, when the king's most excellent majesty, the queen, the prince, and the lords spiritual and temporal, and commons, should have been assembled in the upper house of Parliament upon the fifth day of November in the year of our lord 1605 suddenly to have blown up the said house with gunpowder, an invention so inhuman, barbarous and cruel, as the like was never before heard of.
The law was repealed on 25 March 1859 by Anniversary Days Observance Act.