Insignia of the Order of the Holy Sepulchre (from Diderot's Encyclopédie. They are A cross potent between four crosslets gules.
The Kingdom of Jerusalem was created in 1098, when the members of the First Crusade captured Jerusalem and elected Godfrey of Boulogne, or Godefroi de Bouillon, duke of Lower-Lorraine, as king of Jerusalem. The city was itself finally taken back by the Muslims in 1291, although the title continued to be claimed for centuries.
The Corpus Inscriptionum Crucesignatorum is online, listing inscriptions from the Crusader times that have been found in the Middle East.
The Arms of the Latin Kingdom of Jerusalem are well-known: Argent a cross potent between four crosses or. It is the most well-known violation of the rule of tinctures.
Whether these arms were ever used by the kings of Jerusalem is another matter. According to an article by Hervé Pinoteau in the Cahiers d'Héraldique, vol. 4, the earliest representation of the cross potents between crosslets is on the seal of a nephew and ward of John of Brienne, king from 1210 (the seal is from 1227). The arms of Jerusalem also appear on a reliquary called "la cassette de Saint-Louis" which he dates to 1236. (See also an article by Elliot Nesterman on early evidence of the Cross of Jerusalem).
The arms of Jerusalem pop up in a number of places. The reason for this is the rather tortuous history of the throne and title. The short version is this: three lines stemmed from Queen Isabeau (d. 1206), the eldest of which ruled in absentia until 1268, at which time the two other lines entered in dispute over the succession. From this dispute stems the claims of (1) the kings of Cyprus and (2) the kings of Sicily. The claim to Cyprus (1) became object of dispute in 1474 as the result of an usurpation: the claims of the usurper (1a) passed to Venice, while those of the displaced ruler (1b) passed to Savoy. As for the claims of the kings of Sicily (2), it became part of the dispute in 1434 between the duke of Anjou and the king of Aragon. The claims of the former (2a) passed briefly to the kings of France (1494-1515) and were later resurrected by the dukes of Lorraine in 1700 (whose descendants became emperors of Austria), while the the claims of the latter (2b) passed along with Sicily itself to the kings of Spain (1506-1700), then becoming the object of yet another dispute until returning to a younger son of the king of Spain in 1738; henceforth the title was used both by the kings of Spain and those of the Two Sicilies.
The kingdom of Jerusalem was founded as a consequence of the 1st crusade of 1099. Godefroi de Bouillon died in 1100 and was succeeded by his brother Baudoin I (+ 1118) and a great-nephew Baudoin II (+ 1131), who left an eldest daughter Mélissende. She passed the throne to her husband Foulques d'Anjou (+ 1147), and to her sons Baudoin III (+ 1163) and Amaury or Amalric (+ 1173). Amaury had a son and successor Baudoin IV (d. 1185), and two daughters, Sybille and Isabeau (1169-1206).
Sybille married in 1176 William of Montferrat (+ 1177), by whom she had a posthumous son Baudoin. She was then married in 1180 to Guy de Lusignan (d. 1194), count of Jaffa and Ascalon who was also appointed regent of the kingdom by the invalid Baudoin IV. But Baudoin IV then changed his mind, took away the regency, and abdicated in 1182 in favor of Sybille's son Baudoin V. This child died in 1186, soon after his uncle, and Sybille became queen of Jerusalem, and was crowned with her husband Guy de Lusignan. However, a rival in the person of Conrad of Montferrat, brother of Sybille's first husband, rose up. In the end an agreement was reached: Guy would retain the title for his life, Conrad would marry Sybille's sister Isabeau and succeed as well as his posterity. By that time, the city itself had actually been lost. Sybille had died in 1190, Conrad was murdered in 1192, leaving only a daughter Marie (1191-1212), and Guy renounced his claim in 1192 and bought the island of Cyprus from Richard Lionheart who had just conquered it from the Byzantine empire.
This left only Isabeau as the heir, and she became queen in 1192. All subsequent claims to the throne of Jerusalem stem from her. She married the same year Henri de Champagne (1166-97), who became king with her and died in 1197, leaving two daughters Alix and Philippa. Queen Isabeau next married Amaury de Lusignan (1145-1205), elder brother of Guy and his successor as king of Cyprus, by whom she had Sybille (married to Leo II of Armenia) and Mélissande. Isabeau died in 1205 and was succeeded by her eldest daughter Marie (1191-1212), married to Jean de Brienne (d. 1237) in 1209. Their only daughter Isabeau (1211-28) was married to the Emperor Frederic II who forced his parents-in-law to turn over the throne to him in 1225. Frederic was succeeded as Emperor and king of Jerusalem by his only child of that marriage, Conrad (1228-54), himself succeeded by his only child Conradin of Hohenstaufen 1252-68), who lost his throne of Naples and his life to Charles of Anjou. With him the issue of queen Isabeau's first daughter died out.
The Hohenstaufens were ruling in absentia, and their rule was not liked. The local barons managed to induce various people to claim the regency. Alix de Brienne, second daughter of queen Isabeau, had married Hughes de Lusignan (d. 1218), son of Amaury by a previous wife, and king of Cyprus. Alix died in 1246 and her son Henri (1218-53) succeeded her as regent of Jerusalem. At his death, his son grandson Hugues II (1252-67) was a minor and the widow Plaisance (d. 1261) was regent of both Cyprus and Jerusalem. At her death, a new regent was required; the late king Henri had two sisters Marie (d. 1252) married to Gauthier de Brienne, and Isabelle (d. 1264), married to Henri de Poitiers. The elder one's son, Hugues de Brienne, was passed over in favor of the younger one's son Hugues d'Antioche as regent of Cyprus, while Isabelle herself was accepted as regent for Jerusalem. On her death in 1267, Hugues de Brienne's attempt to claim his rights was rebuffed and the throne of Cyprus, along with the regency of Jerusalem, passed to Hugues d'Antioche, whose descendants assumed the name of Lusignan and reigned over Cyprus.
At the death of Conradin, the issue of Queen Isabeau's eldest daughter became extinct. Hugues III of Cyprus, descended from her second daughter and already regent, now claimed the throne. But another claim emerged through the third daughter of Queen Isabeau, Mélissende, who married Bohémond IV of Antioch (uncle of Hugues III) and whose only daughter Marie of Antioch claimed the throne as being closer in kinship to Isabeau. She was unsuccessful and Hugues III was crowned king of Jerusalem in 1269. She went to Rome to plead her case with the Pope, and was eventually induced to cede her rights in 1277 to Charles of Anjou, whom the pope had established as king of Naples and Sicily (the same who had defeated Conradin in 1268). Henceforth there were two lines of claimants, the kings of Cyprus and the kings of Naples.
The kings of Cyprus continued to be crowned kings of Jerusalem, although from 1277 to 1282 the remnants of the kingdom (Acre) were actually under Charles d'Anjou's control, and the kings of Cyprus only gradually restored their authority. But soon after, with the fall of Acre in 1291, there was nothing left of the kingdom of Jerusalem. In 1458 Jean III, last male of the line, died without male heirs. His only sister Anne had (d. 1462) married Louis I de Savoie. His only daughter Charlotte (d. 1487) was recognized as queen of Cyprus, Armenia and Jerusalem, and married to her first cousin Louis de Savoie. But she was dethroned in 1460 by a bastard son of her father, namely Jacques II (d. 1473), and fled to Italy. Ultimately, in 1485, she ceded her rights to her husband's nephew Charles I, duke of Savoie, and his successors; at that point the dukes of Savoie (later kings of Sardinia and kings of Italy) added the title of king of Jerusalem, Cyprus and Armenia to their titles and the arms to their achievement. The kings of Italy used the title until 1946.
Jacques II died in 1473, leaving a widow Caterina Cornero (1454-1510), from the Venitian aristocracy. His posthumous son Jacques III soon died. The city of Venice turned Cyprus into a protectorate, and, in 1489, forced Caterina Cornero to return to Venice and cede her rights to the Republic. From then on, the Republic of Venice also added the title and arms of Jerusalem, Cyprus and Armenia to its own, until 1797 when the Republic was abolished and its territories handed over to Austria by the Treaty of Campo-Formio. Cyprus was under Venetian control until 1571 when it was conquered by the Turks. Venice became part of the kingdom of Italy in 1866.
Meanwhile, the kings of Sicily also claimed the title of king of Jerusalem. In 1282, Charles d'Anjou lost Sicily and his descendants reigned in Naples only (albeit under the title of kings of Sicily) while Sicily itself was ruled by branches of the house of Aragon. When the descendants of Charles d'Anjou became extinct in 1434, the two claimants were René d'Anjou and Alfonso, king of Aragon and Sicily, and the latter won, at which point his successors the kings of both Sicilies added the claim of Jerusalem to their own. René's claim was resurrected by his grand-nephew king Charles VIII of France in 1494, who managed to conquer and briefly hold Naples, and who used the title of Jerusalem, as did his successor Louis XII (but no other French king did so). In 1506 the Two Sicilies was finally regained by king Ferdinand of Aragon, and henceforth possessed, along with the claim to Jerusalem, by the kings of Spain, descendants of Fernando's daughter Juana and her husband Philip of Habsburg, until their extinction in male line in 1700.
As a result of the war of Spanish Succession (1701-13), Naples and Sicily were ceded by Spain to the Habsburg emperor Charles VI in 1720, and the pope duly invested the emperor with the titles of king of Sicily and Jerusalem on June 5, 1722 (the kingdom being a papal fief). In the course of the war of Polish Succession (1733-38), the younger son of the king of Spain, Don Carlos, managed to conquer the Two Sicilies, a conquest recognized by the peace of Vienna of 1738, and by the pope in the same year. Carlos became king of Spain in 1759 and left Naples and Sicily to his younger son Ferdinand, whose descendants reigned until 1860. The kings of Spain continued to use the title of Jerusalem until 1931, as did the kings of Two-Sicilies.
On the other hand, René's daughter Yolande married Ferry de Vaudémont, one of whose sons became duke of Lorraine. The modern house of Lorraine took up the claim to Jerusalem in 1700 (although it wasn't the best claimant from a genealogical point of view, as pointed out by W. A. Reitwiesner) when duke Leopold returned to his duchy after 28 years of French occupation, and adopted a closed royal crown and the style of king of Jerusalem. His son François, duke of Lorraine, married the Empress Maria-Theresa, and their descendants as rulers of Austria inherited the claim. The arms of Jerusalem could be seen in the grand arms of State of the Austrian Empire in the 19th century and the title was used until 1918.
There is very little evidence on the arms of the Crusader states. The traditional arms of the kingdom of Jerusalem are not known before the 1230s, when the city had already been lost. Numismatic evidence is scant, epigraphic evidence even more so (there are very little heraldic traces of the Crusaders in the Middle East, outside Cyprus; see an interesting exception).
The best work is Gustave Schlumberger's Numismatique de l'Orient Latin (Paris, 1878; reprint Graz 1954). In a coin auction catalogue I recently received, coins from Tripoli feature:
Coins of Antioch feature:
Interestingly, coins from Cyprus (1306-1473) constantly feature on the reverse a cross potent between four crosses, never crosslets but sometimes patty or formy. But what is peculiar is that the main cross is "quadrat in the centre", that is, its center is thickened by a square. This is, according to Parker's Glossary, called a cross of S. Chad, because it features in the arms of the see of Lichfield and Coventry, of which S. Chad was the first bishop. The quadrating on the Cyprus coins is much less pronounced than in the drawing in Parker, but this is nevertheless quite intriguing.
There is more armory from Cyprus and Constantinople; but then, those arms are well known. The Courtenay arms appear on Philippe de Courtenay's seal (d. 1283). Interestingly, the earlier emperors of Constantinople, Baudoin of Flanders (d. 1205), Henri I (d. 1216), Baudoin II (d. 1261) all use the lion of Flanders, although one contemporary cronicler describes Henri riding in battle with a coat-armour gules semy of crosses or. Villehardouin, princes of Achaia, use the family arms of a cross recercelee; later, Louis a cadet of Burgundy who claimed Achaia added a quarter of Villehardouin to his arms of Burgundy ancient (14th c.). Achaia was also claimed by a junior branch of Savoy, who differenced with a bend.