The biblical story of Judith has all the ingredients to make a great opera. Sex, debauchery, drunkenness, intense patriotism and a climatic decapitation all provide a riveting story that deserves Richard Strauss' masterly dramatic touch. Scarlatti, Parry, Mozart and even Honegger had a go at it but it was Antonio Vivaldi's loyalist allegory which drew the committed and curious to the superb Teatro La Fenice in Venice.

The story line is straightforward. Judith is a Second Temple period Zionist zealot, femme fatale par excellence and progenitor of the ladies' division of Mossad. A kind of pre-Masada Merry Widow with a machete. She enters the camp of conquering Assyrian general Holofernes with the intention of using her seductive wiles to catch him off guard and give the bibulous bounder his just deserts – in this case the nifty separation of his priapic torso from his bellicose pate. The two central characters are aided and abetted by a devoted eunuch (Vagaus) and a loyal maid Abra (minus cadabra). There is also the role of Ozias, High Priest of Bethulia which is in fact a place which never existed. A chorus of drunken Assyrian soldiers and nubile Bethulian maidens, all singing in pure Livian Latin, complete the dramatis personae.

From an aural point of view, this should be fine except for the fact that in writing this oratorio militare sacro in celebration of the revered repubblica Serenissima's victory over the snivelling Turks on Corfù in 1716, Vivaldi used the resources of his girls-only orphanage-cum-convent-cum-music school known as the Ospedale della Pietà.  This meant that all the roles – male, female, boozy barbarians and virginal damsels – were sung by women. The ultimate trouser role opera and a dream for sisters of Sappho.

The only problem is that with the five principal roles sung by three contraltos and two sopranos, the vocal tonalities are at best confusing and at worst, monotonous. Far greater tonal variation and interest comes from the orchestration which includes theorbos, viola d'amor, bass viols, chalumeaux, mandolins and an almost calliope-sounding small organ. 

The Baroque orchestra of La Fenice, playing at parterre level, was led by Alessandro de Marchi and produced some wonderful sounds, despite frequent intonation problems in the higher strings. Stirring trumpet playing in the opening D major “Arma, caedes, vindicatae, furores” chorus with really marvellous trills established the celebratory military nature of the opus from the outset. The mandolin obbligato and pizzicato string accompaniment to Juditha's enchanting “Transit aetas” aria was subtle and delicately phrased. The rhythmic lark-like major fourth intervals from solo chalumeau in Juditha's “Veni, me sequere fida” was also particularly memorable while fine oboe playing in Holofernes' following “Noli, o cara, te adorantis” scena was similarly impressive. The orchestra seemed to spring alive during Vagaus' electric C minor presto “Armatae face” aria when he suffers the understandable shock of finding his master without a head. The rhythmic marcato and sforzando articulation was played with passion and precision.

Although Juditha and Holofernes are clearly the principal characters in the opera, the secondary roles of Abra and Vagaus have plenty to sing as well. Unlike Caravaggio's concept of Juditha's servant and partner in crime as a vicious malevolent old hag, Vivaldi's Abra is a light lyric soprano with some mellifluous long phrases to manage, such as “Non ita reducem” in Act II. The role was sung by Giulia Semenzato with competence if not great distinction. On the other hand, the most impressive singing of the evening came from Paola Gardina as Vagaus. “Armatae face” was delivered with a crisp, even coloratura and some really plummy low C naturals. “O servi, volate”, with rhythmic mandolin then choral accompaniment, was memorable for her accurate ornamentation and excellent projection.

As the ill-omened Assyrian general, Teresa Iervolino seemed more likeable than loathsome, although Vivaldi's scoring for the role is a long way from the Alberich or Hagen-esque orchestration of evil which Wagner painted some 140 years later. “Nox oscura tenebrosa” with gentle string and organ accompaniment could not have been more endearing.

In the title role of Juditha, Manuela Custer displayed impressive breath control with a formidable chest and lower register, especially in “Vivat in pace” and “In somno profundo”.  The descending forte chromatic passages on the word “plorando” in “Agitata, infido, flatu” were gutsy and biting and sounded more suitable to hateful Holofernes than the belle of Bethulia, but somehow Signora Custer failed to please. It seems the mercurial Venetian audience preferred the barbarians on this occasion.

The minimalist production by Elena Barbalich was enhanced with excellent lighting by Fabio Barettin and there were a number of impressive stage images. Unfortunately Holofernes’ oft-paraded scalp looked like a cheap carnival mask found the Piazza San Marco. As debauched and inebriated Assyrian soldiers, the chorus was about as dangerous as a group of tiddly St Trinian’s schoolgirls.

Despite the inherent tonal uniformity of an all-female cast, Juditha triumphans is a work which definitely beguiles with further hearings. Viva Vivaldi.