The olive branch appears with a dove in early Christian art. The dove derives from the simile of the Holy Spirit in the Gospels and the olive branch from classical symbolism. The early Christians, according to Winckelmann, often allegorised peace on their sepulchres by the figure of a dove bearing an olive branch in its beak. For example, in the Catacomb of Priscilla in Rome (2nd – 5th centuries CE) there is a depiction of three men (traditionally taken to be Shadrach, Meshach, and Abednego of the Book of Daniel) over whom hovers a dove with a branch; and in another of the Roman catacombs there is a shallow relief sculpture showing a dove with a branch flying to a figure marked in Greek ΕΙΡΗΝΗ (Eirene, or Peace).

An olive branch held by a dove was used as a peace symbol in 18th century Britain and America. A £2 note of North Carolina (1771) depicted the dove and olive with a motto meaning: "Peace restored". Georgia's $40 note of 1778 portrayed the dove and olive and a hand holding a dagger, with a motto meaning "Either war or peace, prepared for both." The olive branch appeared as a peace symbol in other 18th century prints. In January 1775, the frontispiece of the London Magazine published an engraving: "Peace descends on a cloud from the Temple of Commerce," in which the Goddess of Peace brings an olive branch to America and Britannia. A petition adopted by the American Continental Congress in July 1775 in the hope of avoiding a full-blown war with Great Britain was called the Olive Branch Petition.

Source: Olive branch from Wikipedia

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