The Dessau Bridge

Dessau 1626 by Warlord156

The battle for the Dessau bridge in 1626, from the Theatrum Europaeum The legend to the small letters on the plan reads: A. Imperialist fortifications; B. Elbe bridge; C. Imperialist redoubts; D. Mansfeld’s camp; E. Mansfeld’s fortifications; F. Mansfeld’s approach trenches; G. Imperialist approach trenches and redoubts; H. Aldringer’s approach trenches; I. Position held against Mansfeld; K. Imperialist artillery; L. Mansfeld driven off; M. Imperialist sally; N. Friedland’s cavalry on the near side of the river; O. Mansfeld’s cavalry; P. Friedland’s cavalry; Q. Mansfeld’s flight; R. Friedland commences pursuit; S. Schlick’s and Aldringer’s infantry; Y. The village of Rosslau.

Albrecht von Wallenstein’s appointment as Imperial general had come too late for matters to be concluded in 1625, when a conjunction of his and Johann Tserclaes, Count of Tilly’s forces might have driven the isolated Christian IV back to Denmark and out of the war. Instead they united in time only for the armies to spend the winter skirmishing, looting the countryside, and eating the peasantry out of house and home, rather than achieving anything of military significance. Meanwhile Christian was involved in two contradictory negotiations, one taking place in Brunswick, where peace with the emperor was discussed, and the other in The Hague, where attempts were made to widen the anti-Habsburg coalition in order to continue the war. The peace conference was the first of many occasions upon which Wallenstein favoured a realistic approach in order to achieve a peace settlement, but the hardline Imperialist position was determined in Vienna and Munich, and no progress was made. Matters stood little better for Christian in The Hague as most of his prospective allies did not participate, even though they realised that Wallenstein’s new army completely altered the balance, and that if as a result Christian were defeated or withdrew from the war their interests would be seriously threatened. However England and the Dutch Republic agreed to provide him with money, Ernst von Mansfeld’s army was despatched to Lower Saxony, and contacts were re-established with Bethlen Gabor. The other Christian the Younger of Brunswick, the `mad Halberstädter’, also reappeared on the scene, albeit with a makeshift army of limited military value, while another German prince, Duke Johann Ernst of Weimar, contributed troops to the revived coalition.

There were predictable tensions between the leaders of these diverse forces, at least partly as a result of which their grand plan was based on independent rather than united action. Although this was making a virtue of necessity it was nevertheless a sound strategy, as by separating they prevented Tilly and Wallenstein from combining against them. Mansfeld’s task was to draw Wallenstein away by heading east into Silesia, forcing him – so the plan went – to follow because of the threat this would pose to Bohemia, Moravia and ultimately Austria itself. As in 1623 the intention was that this force from the west would join up with Bethlen Gabor invading from the east, when together they would be strong enough to face and defeat Wallenstein. Meanwhile Christian of Brunswick was to bypass Tilly and move south, before turning and threatening his rear while Christian of Denmark confronted him from the north.

It was not a bad plan, and it also exploited the equally predictable ten- sions between Tilly and Wallenstein, the old, experienced and successful general and the younger unproven leader of a new and unproven army. Rivalry over winter quarters had been the start, but Wallenstein had come off better by moving quickly into the rich lands of the Protestant- held secularised bishoprics centred on Magdeburg and Halberstadt. With Wallenstein thus ensconced by the Elbe, Tilly remained 80 miles to the west on the River Weser, a disposition which determined their respective roles in the campaigns of 1626. There were also differences over strategy. Wallenstein wanted their forces to join up for a decisive attack on Christian early in the year, whereas Tilly preferred to play a waiting game, hoping to trap the Danes between them later in the spring. Wallenstein, closer to Christian’s main army, was thus left at risk should the king move first and attack him in strength. The result was that while the generals were arguing the relative importance of possible lines of attack or defence, each seeking support and troops from the other, they lost the initiative and were forced instead to respond to the opening moves of their enemies. Tilly was soon under pressure, and when the `mad Halberstädter’ threatened the city of Goslar Wallenstein was obliged to assist by leading a large force against him, only to find that the enemy quickly disappeared. He then had to turn back to counter an advance south by a Danish division under General Hans Fuchs, which he chased off after a sharp skirmish but without being able to force a battle. Meanwhile Mansfeld was already across the Elbe.

Rivers were of great strategic importance, not only as the easiest line of advance or retreat using the relatively good roads alongside them, but also as supply lines for bringing up heavy guns, provisions and other necessities by water. However major rivers were also potentially dangerous obstacles, particularly to a retreating army, as bridges were few and far between as well as easily fortified or broken down. Hence over the winter Wallenstein had substantial defences constructed on both sides of the Elbe bridge at Dessau, 30 miles south-east of Magdeburg, and he placed Aldringer there with a garrison to defend it. Magdeburg and its bridge were in Protestant hands, while south of Dessau all the way to the Bohemian border the Elbe flowed through Protestant Saxony, so that securing the bridge was a prudent precaution as well as preventing the river being used as a supply line by the enemy. Nevertheless it was a surprise when in April 1626, after taking the town of Zerbst nine miles to the north-west, Mansfeld mounted an attack on the defences around the northern end of the bridge.

Despite the confident accounts given in many histories it is very difficult to describe accurately what happened at battles in the early modern period. Numbers are the first problem. Contemporary reports give large, round and probably exaggerated figures, and for want of anything better these often pass from one history to the next, eventually becoming accepted as though they were established fact. The starting point in the Thirty Years War was to list the units involved, which were known by the names of their commanders and were usually well recorded, and to tot up their nominal strength, 3000 for an infantry regiment, 300 for a company, and 1000 and 100 for the equivalent cavalry formations. The result was the maximum figure, although the one often reported, but units were rarely at full strength even in total, while after deducting the sick, wounded, missing and dead the numbers available and fit to fight could be very much lower, sometimes half or less. This may not matter, as the same applied on both sides, so that the relative strengths quoted may be somewhere near right even if the absolute numbers are wrong, but it helps to explain the frequent discrepancies between different reports of the same event. Numbers of casualties were even more arbitrary, as the dead were mostly buried in mass graves and perhaps not even counted, while those who failed to return for roll-call and were not known to be prisoners were simply struck off the company lists, so that there was no distinction between casualties and deserters. Prisoners were no better accounted for, usually simply being enrolled by the winning side, and here too the numbers represent the loosest of estimates or perhaps simply guesswork. The most accurate figures after a battle seem to have been the number of enemy standards taken – a particular point of military pride – and perhaps the number of cannon captured.

The course of a battle is often as unclear as the numbers involved. Two hundred years later the duke of Wellington noted `how little reliance can be placed even on what are supposed to be the best accounts of a battle. . It is impossible to say when each important occurrence took place, or in what order.’ There are good reasons for this. Battles were frequently confused affairs, and the participants themselves rarely had a full picture of events, so that subsequent accounts involve piecing together partial, impressionistic and often inconsistent reports to work out what might have happened. The term `battlefield’ is itself misleading, suggesting a conveniently open and something like level discrete area, whereas in fact troops, particularly cavalry, might range widely over territory broken up by streams, ditches, hills, woods, villages and other obstructions to both movement and vision; 10,000 infantry could well be spread out over two miles or more, so that a commander would often not have had a clear view of their disposition. Worse still, once action commenced the guns of the period quickly created `such an awful smoke. that we could scarcely see a pistol-shot in front of us’, as a Bavarian officer recorded after one such engagement.

The battle for the Dessau bridge is a good example of the numbers problem. Mann, in his biography of Wallenstein, puts Mansfeld’s army at 10,000 men, whereas Guthrie calculates less than 7000 in his study of the battles of the Thirty Years War. Of these Mann states that 3000 to 4000 were killed, against Guthrie’s estimate of somewhere over 1000. Conversely Mann reports 1500 taken prisoner against Guthrie’s 3000, so that according to Mann Mansfeld escaped with 5000 survivors while Guthrie says that it was only about 2000. Neither gives figures for Wallenstein’s forces, although Guthrie contends that he had at least twice as many men as Mansfeld, that is upwards of 14,000 by his calculation, whereas Diwald, in his Wallenstein biography, puts his strength at 21,000 infantry and six regiments of cavalry.

The Theatrum Europaeum, a major contemporary chronicle, made a speciality of elaborate copperplate illustrations, including detailed plans of battles commissioned from experienced military officers, and these give very helpful pictures of the terrain as it then was, together with such features as earthworks and other defences. A drawing in the Theatrum shows that the Dessau bridge, which was some distance north of the town, spanned both the Elbe and its wide flood plain. It is depicted as a narrow structure built on piers, with small Imperialist forts on the south side and a substantial defensive enclosure around the bridgehead on the north, and with protective wings and trenches securing a strip of land along the riverbank in both directions. The whole area to the south was heavily wooded, so that the road along which the Imperialist troops approached was well screened from Mansfeld on the opposite side. The fortifications would have largely hidden the bridge itself from him, and Aldringer had also covered it with tree branches, so that troops crossing could not be seen. The land north of the river where Mansfeld made his camp and positioned his forces was much more open, but he had thrown up temporary earthworks opposite and parallel to the Imperialist defences. To the east a belt of woodland started from the river close to the Imperialist right wing, extending northwards and then westwards so that it effectively bounded the whole of Mansfeld’s left flank.

Mansfeld’s initial probes in early April and a more substantial attack a week later showed that although Aldringer had only a small garrison the position had been too well prepared to be easily taken. Mansfeld accordingly brought up guns and set his men to digging approach trenching for a full-scale storm of the bridgehead. His reasons are not well established, but if his plan was to draw Wallenstein after him into Silesia he would have needed a head start so that he could reach Bethlen Gabor before Wallenstein caught up with him. Taking the bridge and leaving a rearguard to defend it would have helped to pre- vent the Imperial army following too hard on his heels. Christian of Denmark was also worried that Mansfeld’s departure would weaken his own position, so that he wanted him first to hamper Wallenstein by cutting his supply line along the river and opening up a potential threat to his rear. Fuchs was charged with supporting the action, but he was still recovering from his own clash with Wallenstein, so that he did not appear on the scene. Hence Mansfeld launched the attack on his own, perhaps tempted by the opportunity of an easy victory over the heavily outnumbered Aldringer. His career had been remarkable more for his ability to recover from setbacks and survive disasters than for any achievements in the field, and he may have wanted a triumph to register with Christian. Successive failed attacks seem only to have made him the more determined to persevere, and to have made him oblivious to the changing balance of forces around the bridge.

Mansfeld’s perversity was Wallenstein’s opportunity. It had been a frustrating winter, and he was well aware that critics in Vienna were saying that in the six months since the novice general set out with his new army nothing of consequence had been achieved. Now there was a chance of action. He could not move too early in case the attack on the bridge was a diversion as part of some larger plan, but once Mansfeld brought in artillery and his main army Wallenstein was ready to respond. The first step was to move up enough reinforcements to prevent Mansfeld gaining a quick success, and Colonel Heinrich Schlick was swiftly despatched with the necessary troops. Schlick managed to get his men over the bridge and into the northern defences either unobserved or with their numbers sufficiently hidden by the screening, so that when Mansfeld attacked on 23 April he encountered much stronger resistance than he had expected and he was obliged to withdraw. Meanwhile Wallenstein moved up his own artillery and a large force of both infantry and cavalry.

The key point in his plan was the wood on Mansfeld’s eastern flank, where the latter had not placed troops either for lack of men or because he did not think it important. On 24 April Wallenstein moved more units over the bridge, including heavy cavalry. Then under covering fire from an artillery battery south of the river, and assisted by a diversionary sally from the west side of the bridgehead defences, his men occupied the wood. Presumably Mansfeld again underestimated their number and strength, as he pressed on regardless, launching a heavy frontal attack on the fortifications early the following morning. Reports indicate that he made several unsuccessful assaults over the next three hours before Wallenstein ordered a counterattack, which was followed by heavy and evenly balanced fighting on the open ground. At the critical stage Wallenstein sent infantry reinforcements over the bridge, and the issue was then decided by a flanking cavalry attack from the wood. To add to the confusion of Mansfeld’s men some of their gunpowder wagons exploded in the rear, so that retreat quickly turned to flight. Mansfeld managed to escape back to Zerbst with many of his cavalry, but most of his surviving infantry were captured.

Wallenstein’s battle plan was well conceived and well executed, following a central principle of military strategy by concentrating superior forces before engaging the enemy. Nevertheless it was a bold undertaking, as getting large numbers of men and horses over a narrow bridge and into a small defended area in the face of the enemy had its own risks, while fighting with their backs to the river left little scope for an orderly retreat had Mansfeld proved the stronger. Wallenstein’s own report was brief and to the point:

Mansfeld and his entire army moved up to the fortifications at the Elbe bridge near Dessau, besieging and bombarding them, to counter which I led the majority of the Imperial army entrusted to me out to meet him, advancing against him from the aforementioned fortifications. Yesterday God gave us the good fortune to defeat him, cutting through his forces and putting them to flight.

He sent an officer to provide a fuller account to the emperor, who was delighted with these `impressive and knightly deeds’, as he enthusiastically wrote in congratulatory letters to Wallenstein and his principal officers.

Ernst von Mansfeld

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