MORNAY, PHILIPPE DE (1549-1623), seigneur du Plessis-Marly, usually known as Du-Plessis-Mornay or Mornay Du Plessis, French Protestant, was born at Buhy in Normandy on Nov. 5, 1549. His mother had leanings toward Protestantism, and, on his father's death in 1559, the family formally adopted the reformed faith. Mornay studied law and jurisprudence at Heidelberg in 1565 and the following year Hebrew and German at Padua. His career as Huguenot began in 1571 with the work Dissertation sur l'eglise visible, and as diplomatist in 1572 when he undertook a confidential mission for Admiral de Coligny to William the Silent, prince of Orange. He escaped the St. Bartholomew massacre by the aid of a Catholic friend, and took refuge in England. Returning to France in 1573, he fought under Henry of Navarre. He was taken prisoner on Oct. Io, 1575, but not being recognized was ransomed for a small sum. Shortly afterwards he married Charlotte Arbaleste at Sedan. Mornay was gradually recognized as the right-hand man of the king of Navarre, whom he represented in England from 1577 to 1578 and again in 158o, and in the Low Countries 1581-82.
After the death of the prince of Conde in 1588 Mornay's in fluence became so great that he was popularly styled the Hugue not pope. He was present at the siege of Dieppe, fought at Ivry, and was at the siege of Rouen in 1591-92, until sent on a mission to the court of Queen Elizabeth. He was bitterly disappointed by Henry IV.'s abjuration of Protestantism in 1593, and thence forth gradually withdrew from the court and devoted himself to writing. He founded in 1593 the Protestant academy or university at Saumur, which had a distinguished history until its suppression by Louis XIV. in 1683. In 1598 he published a work on which
he had long been engaged, entitled De l'institution, usage et doc trine du saint sacrement de l'eucharistie en l'eglise ancienne, con taining about 5,000 citations from the scriptures, fathers and schoolmen. Du Perron, bishop of Evreux, afterwards cardinal and archbishop of Sens, accused him of misquotation, and a public disputation was held at Fontainebleau on May 4, 1600. Decision was awarded to Du Perron. Mornay was deprived of the governorship of Saumur at the time of the Huguenot insurrection in 1621, and died in retirement on Nov. is, 1623.
See the life of Mornay written by his wife for the instruction of their son, Memoires de Mme. Duplessis-Mornay, vol. i. in the ed. of Memoires et correspondences de Duplessis-Mornay (Paris, 1824-25).