Valperga’s fort on the Isoletto

Few realize today, that had Grand Master Nicholas Cotoner (reigned 1663-1680) and his military order of Hospitaller knights


possessed greater resources in 1670, or perhaps, had adopted a different set of priorities, then there would probably be a totally different fort from that which now stands on the Isoletto (Manoel Island),  inside Marsamxett harbour. Indeed, if Cotoner’s vast and ambitious scheme for the defence of Valletta and its harbours had been fully implemented, we would probably be confronted, rather than by the familiar French-designed Fort Manoel, with a more sombre work of fortification designed all’ Olandese by the Italian military engineer Antonio Maurizio Valperga.



Like most works of fortification that never made it off the drawing board or never went beyond the design and concept stage, Valperga’s unrealized project of 1670 for a fort on the Isoletto has attracted little attention to date.  This short article, with its accompanying three-dimensional computer animated reconstructions and graphics is the first in a series of illustrated features designed to bring to life forgotten fortification projects that were proposed by the Order’s many military engineers but never executed - the ‘what-ifs’ of Hospitaller military architecture, so to speak.

The Isoletto.

Valperga’s proposal for a fort on the Isoletto formed part of his overall master plan for the defence Valletta and its harbours which was commissioned by Grand Master Cotoner in 1670, following the traumatic fall of Venetian Candia to the Turks in the previous year. The fort was designed to fulfil an important role in the defence of Valletta and its northern harbour. As a matter of fact, the need for such a stronghold inside Marsamxett harbour had been felt ever since the knights began to build their new convent on Mount Sceberras in 1566.  From that moment onwards, the strategic threat that this small leaf-shaped island began to pose to the western flanks of the new city became all too evident and the issue could not be ignored.

Already by 1569, we encounter a report entitled ‘Discorso sopra le fortificatione, written by an anonymous Cavagliere di Malta, which clearly points out that the enemy could attack Valletta from Marsamxett Harbour and bombard St Michael’s bastion from the Isoletto with relative impunity if no action was taken to fortify the place. In his recommendations, the Cavagliere di Malta proposed the construction of a gun platform (‘piattaforma’) with ‘due teste dipendente, affine che nella batteria che vi si facesse sempre vi restasse piazza di buona forma.’ This small fort, consisting of a cavalier surrounded by a detached low battery, was to be surrounded by a glacis but this work was never taken in hand even though the threat posed by the ‘Isoletto assai eminente’ was again demonstrated by Scipione Campi in 1577 and by Giovanni Battista in 1582.


In 1643 the land on the Isoletto, which then belonged to cathedral chapter of Mdina, was acquired by the Order of St John in order to enable the knights to build a Lazzaretto, or quarantine hospital, but the Isoletto itself still remained unfortified and open to attack. The general emergency created by the fall of Candia to the Turks in 1669, however, brought the danger posed by an unfortified little island once again to the fore and led to the first true design for a fort, produced by Valperga. Its construction, however, came low down the Order’s list of priorities, which was then largely concerned with the completion of the unfinished schemes protecting the Grand Harbour area.  Furthermore, the criticism levelled at Valperga’s proposed design by Count Vernada and the Order’s resident engineer, Mederico Blondel, in 1671, as being too small for its intended role, did not help to promote the project either. By the 1680s, interest in Valperga’s scheme had all but evaporated and this prompted another visiting military engineer, Don Carlos de Grunenberg, in 1682, to design a larger fort with a ‘falsabraga, assi a los dos flances, como a la cortina, su fosso abierto, ravelin, estrada en cubierta, y explanada, y la demas obra que la revine. Once again, however, the Order’s heavy and burdensome commitment to the construction of many unfinished schemes, including the vast Cottonera enceinte, Fort Ricasoli, and the Floriana faussebraye and crowned-hornworks, effectively ruled out any further attention to the problem of the defence of the Isoletto.  It was only with the arrival of the French military mission in 1715, headed by Brig. Rene Jacob de Tigne’, that the Order’s attention was once again directed towards the unresolved defence problem posed by the Isoletto. The French engineers proposed and designed various schemes for the defence of the little island but eventually settled for a small square-planned fort with four corner bastions and a ravelin.  However, another decade had to pass by before work on this fort, named Fort Manoel, was finally taken in hand.

Valperga’s Fort


Although no detailed architectural plans of Valperga’s proposed fort have survived, its basic plan is illustrated very clearly in Vincenzo Maria Coronelli’s Citta’ e Fortezza di Malta colle nuove e proposte fortificationi (Venice, 1688), which depicts a map of Valletta and its fortified harbours, and which most modern historians agree represents Valperga’s scheme (shown above). The proposed fort is also described by Valperga himself in one of the reports that he presented to the Congregation of War. Together, these documents provide enough information to allow a basic reconstruction of the proposed structure and show that Valperga’s Isoletto fort had an interesting design that utilized many of the features and design solutions adopted by him in his other major fort that was actually built at the mouth of the Grand Harbour – Fort Ricasoli.

Like the latter, the Isoletto fort was designed all’ Olandese, that is, in the Dutch style, and is immediately recognised as such by the relatively short curtain walls and the use of aggressive outerworks.  The design for the Isoletto has two main features – a bastioned land front in the form of a crown work,  and a tenaille trace facing  the harbour entrance. Both these design solutions were adopted in Fort Ricasoli, albeit in a different configuration fitted to the nature of the site.  At the Isoletto, however, Valperga sought to reinforce the land front of the proposed fort with a small hornwork, a device which he had also introduced to Malta and which he  incorporated into a section of the Floriana enceinte in order to strengthen the land front ahead of St Francis Ravelin.  At Floriana, however, the hornwork was much larger than the one designed for the Isoletto and, furthermore, was itself protected by an opera coronata to form the crowned-hornworks known as La Galdiana.

Unlike Fort Ricasoli, which occupied a long peninsular site, the proposed fort on the Isoletto adopted a circular rather than an elongated plan. Moreover, the proposed structure was to occupy only part of the terrain provided by the isoletto.  Valperga sought to exploit the higher ground in the third quarter of the island, and in so doing, ensuring that most of the ramparts were carved solidly out of the bedrock.  As a matter of fact,  Valperga’s works at both Ricasoli and the Floriana enceinte (the faussebraye and the crowned-horn works) both sought to exploit the rocky nature of the ground.  The proposed work on the Isoletto was to be surrounded by a rock-hewn ditch and a continuous covertway which extended down, in the form of a caponier, to link up with the Lazzaretto, the quarantine compound situated along the shore of the Isoletto, facing Ta’ Xbiex.  Like Fort Ricasoli, the fort on the Isoletto was to be both a hollow work (i.e. its piazza was to stand at a lower level than the platforms of the enveloping ramparts) and also  an open work, designed to be commanded from the bastion on the higher ground of  Valletta across the harbour to the south.

Indeed, in his short report, Valperga advised the knights to ensure that in the construction of the ramparts and ditch of the proposed fort, the engineers entrusted with the task were to follow the same proportions and dimensions adopted at Fort Ricasoli; ‘Nella costruttione de rampari del ditto fortino s’osserveranno le proportioni contenute nel secondo ramparo attorno del posto Ricasoli, tanto nelle grosezze, altezze, de muri quanto nelle larghezze, et altezze de fossi.’

Valperga’s instruction also refer to what he calls a tenaglia ( tenaille) placed in front and lower than the main ramparts. This ‘Tenaglia’ is probably the same short hornwork shown in Coronelli’s map and mentioned earlier in this article; ‘Con osservanza che la Tenaglia avanti al suo ramparo pigliara forma simile del ramparo de le mezelune del ditto Forte Ricasoli, avertendo che detta Tenaglia rimangha piu’ bassa del ramparo d’una Canna con la construttione della sua fossa simile in larghezza, et altezza di  quello Avanti il ditto ramparo di ditto fortino et il tutto in modo e forma che si vede dissegnato nel dissegno rimesso a’ Sua Eminenza.’  Unfortunately, that drawing has not yet been traced.


The 3D computer graphic reconstruction shown below is designed to translate the plan of the fort on the Isoletto shown in Coronelli’s map into a three-dimensional structure.

JavaScript is disabled!
To display this content, you need a JavaScript capable browser.

Dr. Stephen C Spiteri PhD - (C) 2011


Dr. Stephen C Spiteri

Latest Articles








Date and Time to be 

announced soon


~ Additional Features ~