Raymond was captured during an invasion by Imad ad-Din Zengi, atabeg of Mosul, who gained the two important castles of Montferrand (at present-day Baarin in Syria) and Rafaniya in exchange for his release in the summer of 1137.

Since his army proved unable to secure the defence of the eastern borders of his county, Raymond granted several forts to the Knights Hospitaller in 1142.

Alfonso Jordan's illegitimate son, Bertrand, actually seized the fortress of Areimeh in the County of Tripoli in 1149, but Raymond recaptured it with the assistance of Muslim rulers.

[10] Lewis emphasizes that Kamal al-Din's report is doubtful, because Bazwāj had almost annihilated the army of Tripoli, preventing Raymond from launching major campaigns.

[10] After Zengi laid siege to Montferrand,[11] Raymond sent envoys to King Fulk of Jerusalem, his maternal uncle and brother-in-law, urging him to hurry to the besieged fortress.

[12] Fulk and Raymond of Tripoli decided to launch an assault on Zengi's forces before marching to Antioch, because they thought they could easily defeat the atabeg.

[13][14] Those besieged in the fortress did not know of these movements but readily agreed to hand over the castle to Zengi in exchange for a safe passage and the release of Raymond and all other Christian captives.

[20][21] When establishing a military order on the eastern borderland, Raymond only wanted to secure the defence of his county, but his magnanimous grant laid the foundation of an almost independent ecclesiastic state.

[26][27] Because of his unexpected death, gossip about his murder started spreading among the Crusaders,[28] although he most probably died of natural causes, as a consequence of his lengthy voyage across the Mediterranean Sea.

[29][30] An anonymous Syrian chronicler accused Raymond of the crime, stating that he poisoned Alfonso-Jordan because he feared that his uncle had come to seize Tripoli.

[26] Lewis emphasizes, the chronicle "is hardly the most reliable piece of evidence, so some skepticism about Raymond's involvement in Alfons's death is surely advisible".

[26] Another contemporaneous author—the continuator of Sigebert of Gembloux's chronicle—was convinced that Raymond's sister-in-law Queen Melisende of Jerusalem had poisoned Alfons-Jordan because she wanted to prevent him from claiming Tripoli.

[41][42] In December, Crusader troops invaded the Beqaa Valley, seizing prisoners and booty during their campaign before the Muslim governor of Baalbek routed them.

[47][48] Raymond rode out with them for a short distance, and on his way back to Tripoli, he was killed by a group of Assassins—fanatics employed by the head of the Nizari to murder their enemies[49]—at the southern gate to the city, along with two of his knights.

[4] According to historian Peter Lock, it took place in the spring of 1133, after her brother-in-law, Fulk of Jerusalem, provided military assistance to Raymond's father against Zengi.

[53] Raymond and Hodierna's daughter, Melisende, was famed for her beauty, but her delicate health and rumours about her mother's possible infidelity prevented her marriage to the Byzantine Emperor Manuel I Komnenos.