"The Roman Emperor Trajan, being of an impetuous and active temperament, seemed to be filled with resentment that his realm was not unlimited, but was bounded by the Ister River [Danube]. So he was eager to span it with a bridge that he might be able to cross it and that there might be no obstacle to his going against the barbarians beyond it. How he built this bridge I shall not be at pains to relate, but shall let Apollodorus of Damascus, who was the master-builder of the whole work, describe the operation."
Procopius, Buildings (IV.6.12-13)
In this passage, Apollodorus is described as architekton, the only time in the book that the word is used by Procopius. Otherwise, mechanikos ("master-builder) is used of the builders who served or assisted Justinian in his undertakings, the implication being that the emperor had a greater share of responsibility for such work than his predecessors. (Curiously, having made this distinction, the translator still renders architekton as "master-builder"). Procopius, too, is the only source who indicates Apollodorus to be from Syria, where Trajan had served as a military tribune while his father was governor of that province.
The treatise referred to by Procopius has not survived, but Cassius Dio does provide a description of the bridge, which was constructed during the First Dacian War (AD 101-102).
"Trajan constructed over the Ister a stone bridge for which I cannot sufficiently admire him. Brilliant, indeed, as are his other achievements, yet this surpasses them. For it has twenty piers of squared stone one hundred and fifty feet in height above the foundations and sixty in width, and these, standing at a distance of one hundred and seventy feet from one another, are connected by arches. How, then, could one fail to be astonished at the expenditure made upon them, or at the way in which each of them was placed in a river so deep, in water so full of eddies, and on a bottom so muddy? For it was impossible, of course, to divert the stream anywhere. I have spoken of the width of the river; but the stream is not uniformly so narrow, since it covers in some places twice, and in others thrice as much ground, but the narrowest point and the one in that region best suited to building a bridge has the width named. Yet the very fact that river in its descent is here contracted from a great flood to such a narrow channel, after which it again expands into a greater flood, makes it all the more violent and deep, and this feature must be considered in estimating the difficulty of constructing the bridge. This, too, then, is one of the achievements that show the magnitude of Trajan's designs, though the bridge is of no use to us; for merely the piers are standing, affording no means of crossing, as if they had been erected for the sole purpose of demonstrating that there is nothing which human ingenuity cannot accomplish. Trajan built the bridge because he feared that some time when the Ister was frozen over war might be made upon the Romans on the further side, and he wished to facilitate access to them by this means. Hadrian, on the contrary, was afraid that it might also make it easy for the barbarians, once they had overpowered the guard at the bridge, to cross into Moesia, and so he removed the superstructure."
Roman History (LXVIII.13)
Trajan's chief military engineer in the Dacian Wars (AD 101-106), Apollodorus later turned to civil engineering and architecture and was responsible for Trajan's Forum. Indeed, the placement of the Basilica Ulpia suggests that it may derive from the plan of a legionary encampment, which had its headquarters (principia) placed in the center of camp, behind which was the sacellum, the regimental shrine. Apollodorus also may have been responsible for Trajan's Column and has been credited, as well, for the design of the Pantheon, which was rebuilt by Hadrian, with whom he also worked.
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Even though Dio remarks that the stone piers of the Danube bridge still were standing in his own day, more than a hundred years later, his description must be exaggerated when he remarks that the arches that separated the twenty piers each spanned one hundred and seventy feet and that the piers, themselves, were sixty feet wide. Not counting the abutments on the banks, the length of such a bridge would measure 4770 feet--nine-tenths of a mile. The sestertius illustrated here dates from about AD 105 and likely commemorates the bridge, symbolizing it with a single span. One can see the fortifications or castra that guarded access to the bridge itself. The coin is from the Freeman & Sear Catalog 12 (2005), item 561. |
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Apollodorus later was imprudent enough to criticize Hadrian's design for the Temple of Venus and Rome:
"But he first banished and later put to death Apollodorus, the architect, who had built the various creations of Trajan in Rome—the forum, the odeum and the gymnasium. The reason assigned was that he had been guilty of some misdemeanour; but the true reason was that once when Trajan was consulting him on some point about the buildings he had said to Hadrian, who had interrupted with some remark: 'Be off, and draw your gourds [the concave segments of which, in fact, do recall a type of dome that appears at this time]. You don't understand any of these matters.' (It chanced that Hadrian at the time was pluming himself upon some such drawing.) When he became emperor, therefore, he remembered this slight and would not endure the man's freedom of speech. He sent him the plan of the temple of Venus and Roma by way of showing him that a great work could be accomplished without his aid, and asked Apollodorus whether the proposed structure was satisfactory. The architect in his reply stated, first, in regard to the temple, that it ought to have been built on high ground and that the earth should have been excavated beneath it, so that it might have stood out more conspicuously on the Sacred Way from its higher position, and might also have accommodated the machines in its basement, so that they could be put together unobserved and brought into the theatre [presumably the Colosseum] without anyone's being aware of them beforehand. Secondly, in regard to the statues, he said that they had been made too tall for the height of the cella. 'For now,' he said, 'if the goddesses wish to get up and go out, they will be unable to do so' [the same criticism directed at Phidias' statue of Zeus at Olympia]. When he wrote this so bluntly to Hadrian, the emperor was both vexed and exceedingly grieved because he had fallen into a mistake that could not be righted, and he restrained neither his anger nor his grief, but slew the man."
Dio, Roman History (LXIX.4)
The criticism may have been made in AD 104, before Trajan had departed for Dacia and the fire that year on the Esquiline had made land available for Trajan's baths (Thermae Trajani). Or it may have been two years later, when Trajan returned and construction on his forum began.
Ronald Ridley contends that Hadrian was not responsible for the death of Apollodorus, arguing that, if he had been, the Historia Augusta would have mentioned the fact when it related that the architect was to have assisted Hadrian in the construction of a colossal statue to the Moon (XIX.13). Too, if the Poliorcetica, a treatise on siege engines by Apollodorus, were addressed to Hadrian, it would have to date either to the Danube campaign or the Jewish revolt of Bar Kokhba in AD 132. Since Apollodorus states that he was not familiar with the local terrain, Ridley contends that the uprising in Judea must be intended, which was in response to Hadrian's plan to replace the Jewish Temple with one dedicated to Jupiter (Dio, LXIX.12-14). Apollodorus, then, would have been alive after the Temple of Venus and Mars had been completed.
But the Temple was not dedicated until AD 135 and actually may have been finished by Antonius Pius. As to the Historia Augusta, it recounts that Hadrian, "although he was very deft at prose and at verse and very accomplished in all the arts, yet he used to subject the teachers of these arts, as though more learned than they, to ridicule, scorn, and humiliation" (XV.10). And possibly, to death. The emperor who requested that Apollodorus write his Poliorcetica is not mentioned by name, but references to his talent and kindness suggest that the treatise, in fact, was addressed to Trajan.
Although attributed to Apollodorus, P. H. Blyth argues that two-thirds of the Poliorcetica are later additions, and the original material by a contemporary. In an epistolary preface, the author indicates that he has been asked to supply designs for siege works to be used against an elevated fortified position. And, in a list of contents, he enumerates those that could be used against a hill-fort, including how to deflect objects, such as wagons and barrels, which could be rolled down a hill; screens to protect against missiles when the top is reached; and, once there, advice on undermining a wall, ramming a gate, or using assault ladders. All of these siege works should be "effective, protective, and safe, and that as far as possible all shall be made of easily provided materials, light in weight, well engineered and quick to produce with unskilled labor."
But then the treatise continues with a list of increasing elaborate (and impractical) devices that do not follow these guidelines: hand-held drills; a flame thrower to crack stone; an elevated scouting ladder to look over a wall; a tower that includes a draw-bridge, double ram, a pivoted device to sweep defenders from the wall, a platform to level the ground, and hoses and pumps to fight fires. There also are interlocking ladders that can be assembled to form a scaffold and used with other attached devices, such as a falling knife, a means for dispensing hot oil, and rams, including one with a flail propelled by a torsion spring. There even is an armored floating bridge or raft.
It is this discontinuity between the pragmatic and exotic that convinces Blyth that the latter sections are interpolations to the original material. Because the triangular deflectors and ladders are depicted on Trajan's Column, he also argues that the Poliorcetica was addressed to Trajan, probably at the time of the first Dacian War, which the column commemorates. That it was not by Apollodorus, he attributes to the fact that the author was not prepared to join the campaign, himself, but sent an assistant with a team of skilled workmen.
In the mid-tenth century AD, the Poliorcetica was updated and supplemented by an anonymous Byzantine author, conventionally attributed to "Heron of Byzantium" (after Heron of Alexander, whose work also is discussed). An instructional manual on the fabrication of siege engines and siegecraft (poliorcetics), the Parangelmata Poliorcetica was written for the nonspecialist, the author reinterpreting his sources and adding additional information and explanations: "Having clarified only the works of Apollodorus as it were in toto with additional elaboration and secondary arguements, we have drawn our conclusions, finding and adding ourselves numerous concordant <items>" (I). It is a curious treatise (which understands the Poliorcetica to have been addressed to Hadrian) that describes the battering ram of Hegetor, the largest one in antiquity (XXV; also Vitruvius X.15.2-7), and mentions how the pickled intestines of cattle, attached to wineskins full of water could be used as hoses to spray water on the parts of burning towers that otherwise could not be reached (XXXIX).
The odeum (a hall for musical performance) that was restored by Apollodorus had been built by Domitian (Suetonius, Life, V; Eutropius, VII.2) and, even by the fourth century, still excited wonder (Ammianus Marcellinus, XVI.10.4).
In the relief above from Trajan's Column, Apollodorus' bridge over the Danube can be seen behind the emperor, who holds a patera, a shallow bowl used in sacrifice.
References: Procopius: Buildings (1940) translated by H. B. Dewing (Loeb Classical Library); Dio Cassius: Roman History (1914-) translated by Earnest Cary and Herbert B. Foster (Loeb Classical Library); The Architecture of the Roman Empire (1982) by William L. MacDonald; "Apollodorus of Damascus and the 'Poliorcetica,'" (1992) by P. H. Blyth, Greek, Roman and Byzantine Studies, 33, 127-155; Siegecraft: Two Tenth-Century Instructional Manuals by "Heron of Byzantium" (2000) by Denis F. Sullivan; "The Fate of an Architect: Apollodoros of Damascus" (1989) by R. T. Ridley, in Athenaeum, 67, 551-565. The Poliorcetica of Apollodorus has not been translated into English.
