Conrad von Rosen (29 September 1628 – 3 August 1715) was a soldier from Livonia, who served in the French army under Louis XIV from 1646 on.

In 1689, he went to Ireland with James II of England and commanded the Jacobite troops during the final stage of the unsuccessful Siege of Derry.

Conrad was born on 29 September 1628 at Gross Roop (now Straupe) in Duchy of Livonia (now in Latvia), as the third son[1] of Fabian von Rosen (1590–1633) and his wife Sophia (1597–1673).

As a nobleman's younger son, Conrad von Rosen pursued a military career and in 1644 enlisted in the Swedish army, Livonia at that time being part of Sweden.

He then asked a relative, Reinhold von Rosen, who served in the French army, for a chance to relaunch his career.

Rosen therefore served France in autumn 1678 on the upper Rhine under Marshal Créquy fighting the Imperial army under the Duke of Lorraine.

In 1681, in a climate of increasing religious intolerance before the revocation of the Edict of Nantes, Rosen found it necessary to convert to Catholicism.

[10] He went with him to Dublin and then joined the army in the north, taking part in the Jacobite victory at the crossing of the River Finn, called the "passing of the fords".

On 18 April 1689, Rosen advanced to under the walls of Derry with King James II, who in vain summoned the town to surrender.

Rosen then returned to Dublin with the king, leaving the command of the siege to Lieutenant-General Count Maumont,[citation needed] who was, however, killed about a month later in a sally on 21 April.

He rounded up many Protestant inhabitants of the surrounding countryside who had previously been given legal protections by James and Hamilton, and on 2 July herded them towards the city walls hoping that the sight of them would dispirit the defenders.

Following the landing of Williamite reinforcements commanded by Schomberg and their capture of Carrickfergus, von Rosen advocated abandoning and burning Dublin and retreating behind the River Shannon,[18] a policy that was rejected by James II.

[22] Being now marshal, Rosen sold his charge of maître-de-camp général de cavalerie to François Éléanor Montpéroux.

[24] This gave him the right to wear the blue sash called the cordon bleu that hangs over his right shoulder on his portrait by Hyacinthe Rigaud.