Gertrude of Merania, the queen consort of Hungary as the first wife of King Andrew II (r. 1205–1235), was assassinated by a group of Hungarian lords on 28 September 1213 in the Pilis Mountains during a royal hunting expedition.

According to contemporary sources, Gertrude's blatant favoritism towards her German kinsmen and courtiers had stirred up discontent among the native lords and prompted her murder.

When Andrew II launched a campaign against the Cuman chieftain Gubasel in Bulgaria, Gertrude performed a judicial activity over a lawsuit between Abbot Uros of Pannonhalma and the castle serfs of Pressburg (present-day Bratislava, Slovakia) around 1212 or 1213.

Both remarks imply that Gertrude acted as royal governor both times when Andrew led campaigns in Bulgaria and Halych, respectively,[3][4] which caused resentment among the local elite.

Two other brothers, Ekbert, Bishop of Bamberg, and Henry II, Margrave of Istria, fled to Hungary in 1208 after they were accused of participating in the murder of Philip, King of the Germans.

[6] Although it is possible that the 26th article of the Golden Bull of 1222, which prescribed that Hungarian properties could not be given to foreigners, and the 23rd article of the Golden Bull of 1231, which prescribed that foreigners could only be appointed to court positions if they remained in Hungary (because such people only "take the country's wealth [abroad]"), may reflect a negative response to Gertrude's favoritism,[9] the few surviving royal donation letters from the period do not prove the mass acquisition of land by the Germans either; the local provost Adolph was granted lands in Szepesség due to the intervention of Gertrude and his brothers in 1209, while a certain Lenguer was granted a small portion in the village of Szántó upon the request of Archbishop Berthold.

[10] In order to support his protege Danylo Romanovich against Mstislav Mstislavich, Andrew II departed for a new royal campaign against the Principality of Halych in the summer of 1213.

Late 19th-century Hungarian historian Gyula Pauler was the first scholar, who compiled a professional synthesis, as well as a detailed examination of the circumstances of the murder, based on comprehensive source research and considering the conditions of the era.

A 15th-century section of a Bavarian source, the Founders of the Monastery of Diessen (De fundatoribus monasterii Diessenses) refers the date to 28 September but with the year 1200, and cannot be considered an authentic report.

Pauler argued Andrew II on his way to Halych was caught at Lelesz by the messenger who brought the news of her death, who presented a piece of the queen's corpse as evidence, which was subsequently buried there.

In contrast, Körmendi considered the non-transportable pieces of the mutilated queen were quickly buried in the Lelesz monastery, near which the assassination could have taken place, perhaps in the Patak royal forest along the river Bodrog.

When Duke Béla, gaining power over the royal council, started reclaiming King Andrew's land grants throughout Hungary, he forced his father to confiscate the estates of those noblemen who had plotted against his mother one and a half decade earlier.

Accordingly, Simon "by a new and unheard-of kind of wickedness and vileness, cruelly and horribly armed for hateful machinations, conspiring with his accomplices: bloodthirsty and treacherous men, to the shame and dishonor of our royal crown, was involved in the death of the well-remembered Queen Gertrude, our dearest consort".

[21] The land confiscation in 1228 might be a sign of the subsequent retaliation after an increased role in national politics by princes Béla and Coloman since the early 1220s, as historian Gyula Pauler argued.

Historian Gyula Pauler considered Bánk managed to survive the subsequent retaliation, because Andrew II was not strong enough to punish one of the most powerful barons, while the main assassin Peter, son of Töre was executed.

[28] These works unanimously note John's famous phrase in his letter to Hungarian nobles planning the assassination of Gertrude: "Reginam occidere nolite timere bonum est si omnes consentiunt ego non contradico", can be roughly translated into "Kill Queen you must not fear will be good if all agree I do not oppose".

It is possible that Boncompagno heard the story in the Roman Curia and incorporated it into his rhetoric dissertation and textbook (published in 1235, the first written source of John's alleged letter).

Despite relevant factual errors (e.g. the date), Tamás Körmendi accepted the information of the mid-13th-century annals, since the work provides a very detailed and authentic account of the activities of the Austrian dukes.

[32] A single source, the Chronicle of the Anonymus of Leoben (Chronicon Leobiense) claims that Gertrude's other brother, Ekbert was the one who forced the wife of a Hungarian lord to commit adultery, which resulted the assassination.

[10] The Austrian Rhyming Chronicle is the earliest known work, which preserved the alleged story of that Archbishop Berthold raped Bánk Bár-Kalán's wife, which was the immediate cause of the assassination of the queen, who acted as a procuress in the adultery.

[43] According to a mainstream view of Hungarian historiography, Peter's accomplices, including Palatine Bánk, did not receive severe punishments, due to the current political situation and Andrew's power instability.

When Andrew left Hungary to fight in the Fifth Crusade in 1217–1218, he entrusted the regency to Archbishop John and Palatine Julius Kán, instead of to Yolanda, who remained passive in political matters throughout her life.

[47] While Flórián Mátyás was the first scholar, who collected the narrations in the early 20th century, historians László Veszprémy then Tamás Körmendi organized the sources according to content, determining the philological relationship between them and the time of their origin.

[16] Veszprémy listed those sources within the group, which refer to Peter, son of Töre as the assassin, mention Andrew departure to the Principality of Halych and Archbishop John's famous letter.

Antonio Bonfini, the court historian of King Matthias Corvinus expanded the story in his chronicle Rerum Ungaricarum decades ("Ten Volumes of Hungarian Matters") in the 1490s.

Based on Bonfini's work, the 16th-century Transylvanian chronicler András Valkai wrote the first Hungarian-language epic poem under the title Az Nagysagos Bank Bannak Historia in 1567.

Poet Hans Sachs wrote a tragedy on Ban Bánk under the title Andreas der ungarisch König mit Bankbano seinem getreutem Statthalter in 1561, updating the story to his own age at a few points (for instance, the appearance of the Ottoman Empire as enemy and the theses of the Reformation).

The German poet Ludwig Heinrich von Nicolay wrote a ballad in the subject around 1795, while Johann Friedrich Ernst Albrecht created a dramatic poem (Der gerechte Andreas) in 1797.

Independently from Katona's play and its derivative works, Austrian dramatist Franz Grillparzer wrote his historical tragedy in the subject (Ein treuer Diener seines Herrn) in 1826.

[64] In the play and the opera, the character of Bánk appears as a tragic hero and "defender" of the Hungarian national interests against the "oppressive" Queen Gertrude and her foreign courtiers.