Despite the fame that Herri met de Bles's pictures enjoyed in his lifetime, little is known about his life and confusion still exists as to the precise location of his birth and even the correct formulation of his name. It has been suggested that he was the 'Herri de Patenir' who was recorded in the Antwerp artists' guild in 1535, and that he was possibly a nephew of Joachim Patinir. Very few pictures by de Bles and his studio bear dates and the absence of biographical data frustrates any attempt to determine a detailed chronological order to his oeuvre. Additionally, the sheer number of pictures in de Bles's oeuvre suggest that deviations, both in form and execution, are due to the intervention of one or more collaborators, even though it is evident that they worked very closely under his supervision.
The present painting is exceptional within the artist's corpus. Its sheer size makes it not only his largest known composition, but also one of the largest panels for the genre in the mid-sixteenth century. Moreover, the subject matter is unlike anything previously attributed to de Bles; whilst most of his landscapes contain religious themes, the subject of this picture seems to be purely historical. However, the panel, replete with myriad details of sixteenth century camp life, is entirely consistent with other paintings such as The Conversion of Saint Paul on the Road to Damascus (sold Christie's, New York, 25 January 2002, lot 47) in both its viewpoint and narrative detail. Unlike Patinir, de Bles's mountains rise more naturally from the plains below and his background landscapes are much more atmospheric; subtle cool blues and blue-whites veil the distant prospect, contrasting with the warm greens of the foliage in the foreground. The central rocky outcrop in the present painting also appears in his Landscape with the Sacrifice of Isaac (Cincinnati Art Museum) and Landscape with the Parable of the Good Shepherd (Vienna, Kunsthistorisches Museum).
The subject of the present painting - while open for debate - takes as its source a woodcut of The Siege of Thérouanne (Hollstein XXX, no. 44; see fig. 1) signed with the monogram of Cornelis Anthonisz. (c. 1505-1553). Until recently, it had been assumed that the print depicted the Siege of Thérouanne by the Imperial forces of Charles V in 1553, the year of Anthonisz.'s death, which also would account for the fact that the print remained incomplete. However, both Dr. Peter Martens ('La destruction de Thérouanne et d'Hesdin par Charles Quint en 1553', in G. Bleick et al., La fortresse à l'épreuve du temps, Paris, 2007, pp. 63-117; and doctoral dissertation, Katholieke Universiteit Leuven, 2009, pp. 355-83 and figs. 5.1-33) and Mr. Jan van Helmont (private communication) have convincingly argued that the print actually depicts the earlier, less well-known siege of the city in 1537, thus giving that date as a terminus post quem for the present picture.
Recent infrared reflectography reveals extensive underdrawing that seems to link the initial composition more closely to the print than the finished painting reflects. There are significant changes in design from the drawn to the painted stages, with a different layout of the various encampments as well as a repositioning of the distant ruined castle in the centre from a lower to a higher position (see fig. 2). There is also evidence of 'squaring up', used to transfer preliminary drawings or perhaps the design of the print to the primed panel.
A painting of this size and with this much narrative must have been a specific commission, about which we can only speculate. However, the numerous topographical differences between the print and the painting suggest that rather than this being a contemporary depiction of the siege of Thérouanne, de Bles had chosen to portray an almost generic scene of an army besieging a town. For a painting that should be a historical document there is no identifying inscription; the central rocky outcrop is a fanciful addition to the topography; the depiction of Charles V on horseback just behind the cavalry contingent is imaginary, as he was not present at either the 1537 or the 1553 siege, and the numerous coats-of-arms (with the exception of the Imperial Eagle) and the identifying inscriptions on the tents all appear to be fictitious, while those in the print are real and relate to the protagonists who were present at the 1537 siege.
Above the coat-of-arms on the white tent in the foreground sits an owl, which, from the sixteenth century onwards, has always been taken as the 'hallmark' or signature of works by Herri met de Bles. Gian Paolo Lomazzo (Trattato dell'arte de la Pittura..., Milan, 1584, pp. 475 and 689) refers to the painter as 'Henerico Blessio Boemo, Chiamato de la Civetta [little owl] principal pittore de paesi', while Karel van Mander (Het Schilder-boeck, Amsterdam, 1603/4, fol. 219v) calls him 'Den Meester van den uil' (the master of the owl), adding 'His works can often be found with the Emperor, in Italy and in other places; in Italy they are particularly sought after, for the man with the little owl is very widely famed'.