On the 6th of August in 1870, a French Imperial army was deployed in a pre-selected ‘magnifique’ defensive position around the villages of Froeschwiller and Worth in Alsace, and it was attacked there by a much larger German army of two Prussian and two Bavarian corps. In this battle the French lost twice as many men as the Germans, and were driven from the battlefield in disorder. By contrast, in September 1862 a Confederate army hastily assembled on the west bank of the Antietam creek where it was attacked on the 17th by a much larger Union army. The Confederates resisted successive attacks, inflicted more casualties than they incurred, and remained on the battlefield overnight and through the following day. This paper discusses the reasons for these very different outcomes.
The defending armies in both battles failed to entrench their positions. The French at Froeschwiller did not expect to be attacked, and the Confederates at Antietam were tired after forced marches from South Mountain and Harper’s Ferry. The Confederates did obtain some tactical advantage from defending fences, walls and rocky outcrops, and particularly from a conveniently-aligned sunken road in the centre of the battlefield, while the Union attack was additionally impeded by the limited number of bridges and fords across the Antietam creek
Both battles were fought before the era of smokeless powder, so the clouds of smoke generated by intense firefights would have obscured targets, and would have made it difficult for artillery to fire effectively at long ranges.
Both of the outnumbered armies suffered severe losses. More than half of the French regiments which fought at Froeschwiller sustained losses of over 50% and some units were virtually annihilated; the 2nd Turcos lost 93%, the 75th infantry regiment lost 80% and the 3rd Zouave lost 77% (Turcos and Zouaves were recruited from the native and white populations of French North Africa).
The losses of the Confederate army at Antietam were less horrendous because it was not forced to retreat from the battlefield, and so lost a smaller proportion of soldiers captured. There were 39 Confederate infantry brigades present at Antietam, but in many cases the data on their strength and losses are missing or unreliable. Among the 25 brigades for which credible (albeit approximate) estimates of percentage losses can be derived, it appears that six suffered losses of over 50% (Pryor’s and Evans’ brigades probably both suffered 79%).
Strength of the Armies
At Froeschwiller, as shown below, the Germans had a clear advantage in infantry and artillery. Cavalry (despite its social prestige) was generally ineffective in battles of the late 19th century, notably at Froeschwiller where desperate charges by French cuirassiers were costly and virtually futile, so its numbers can be ignored.
The German numerical superiority in infantry was partially offset by their obsolescent small arms which were out-ranged by the French Chassepot rifles. On the other hand the German numerical superiority in artillery was magnified because their guns and shells were better than those of the French.
It is particularly difficult to define the strengths of the Union and Confederate armies at Antietam because both armies (particularly the latter) had been depleted by straggling during the preceding Maryland campaign, but it is certain that the Confederates were seriously outnumbered.
Strength of the ArmiesTypeConfederateUnionAttacker AdvantageInfantry32,800828002.5/1Cavalry45004300n/aGuns2923781.3/1
Until the arrival of 2500 Confederate reinforcements very late in the battle, the Union superiority of numbers was even larger. The Confederate army’s small arms and artillery were both significantly inferior in quality to those of the Union army.
The weaponry used by the four armies is discussed further in the Appendices.
Why the Union failed to win at Antietam
The obvious and most-often cited reason for the Union army’s failure to achieve a decisive victory was that many of its soldiers (perhaps 30000) were retained in reserve and were never engaged in the battle. General McClellan, commanding the Union army, was chronically cautious; he believed that the opposing Confederate army was much larger than it actually was, and that it was capable of launching a devastating counter-attack at any moment. He knew that his own army was a fragile mix of troops who had experienced defeat more often than victory, and others who had no experience at all. He was also well aware of the hostility of many senior politicians in Washington, and he could expect to be personally blamed and perhaps shot if the Union army were defeated, like French generals during the Revolutionary Wars and (earlier) a British admiral. In these circumstances he was most unwilling to take risks, and kept his most-trusted troops in reserve. By contrast the Crown Prince of Prussia, commanding the Germans at Froeschwiller, knew that his royal blood would insulate him from punishment, whatever the result of the battle.
In this period of military history attacking required more finesse than defence, and was thus more difficult for officers with limited experience. The Prussian army at Froeschwiller had well-trained and experienced officers who understood the established tactical doctrine that whenever a unit encountered enemy forces it should engage them, and that other units hearing firing nearby should move to join the battle; officers could be sure of praise (or at worst of avoiding blame) if they acted according to those precepts. At Antietam most Union generals and field officers were relatively inexperienced, lacked the self-confidence to act on their own initiative to developments in the battle, and preferred to wait for explicit orders which were (inevitably) not always punctual or well-informed. Accordingly the Union army’s attacks at Antietam were not well coordinated in time and space – the Union I, XII, II and IX corps attacked in succession, and most of these attacks did not achieve a local superiority which matched the Unions army’s overall superiority of numbers. McClellan contributed to this incoherence by revising his army’s command structure on the eve of battle, by failing to appoint an overall commander of the three corps forming his right wing, and by adopting an ambiguous plan of action ‘the design was to make the main attack on the enemy left – at least to create a diversion in favour of the main attack, with the hope of something more, by assailing the enemy’s right – and, as soon as one or both of the flank movements were fully successful, to attack their center with any reserve which I might then have in hand’. He also spent most of the battle at his headquarters and directed the battle from a distance. By contrast his opponent, General Lee, rode to view the successive crises in the battle, and personally directed his divisions and brigades to where they were most needed. It is debatable if the potential diplomatic and logistic benefits to the Confederacy justified his earlier decision to campaign in Maryland in the autumn of 1862, but there is no doubt that at the battle of Antietam Lee’s management of his scanty resources forms an outstanding exemplar of a defensive battle by an outnumbered army.
The Confederate and French infantry at Antietam and Froeschwiller respectively resisted attacks by superior numbers, and fought on despite heavy losses. In both battles the defenders did not rely on passive defence but mounted local counterattacks. The Confederate counterattacks successfully disrupted the opposing Union units by killing the foremost officers and men and encouraging the least courageous to absent themselves from the battle. Following such counterattacks, the Union I corps which opened the battle was scattered and unfit for further action for several hours. The French infantry’s counterattacks were similarly gallant but were much less successful because the Germans’ rapid-firing breech-loaders destroyed the advancing French regiments before they could make any significant impact.
At Froeschwiller any French artillery battery which came into action attracted a torrent of German shells, and was soon withdrawn to avoid complete destruction. However at Antietam the Union artillery was using less-effective guns, designed a decade earlier than the Krupp breech-loaders at Froeschwiller, and was consequently unable to suppress the Confederate artillery (though it did inflict heavy losses on the Confederate gunners who remembered Antietam as an ‘artillerists’ hell’). In that battle the losses of most Confederate artillery batteries were not reported separately from the losses of their associated infantry units, but the two battalions of reserve artillery in Longstreet’s ‘corps’ reported average losses of 20% which was probably typical. In other battles of the American Civil War the artillery generally incurred losses of 5 – 10% and it was regarded as acceptable to withdraw a battery when its losses exceeded that range. At Antietam the Confederate army had 8 guns per 1000 troops, which is double the normal proportion, and although these guns were outclassed in counter-battery fire they remained in action until they could use their devastatingly-effective canister on the advancing Union infantry.
In the later stages of the battle of Antietam, when the Confederate troops had been driven back about half a mile, most of the Union artillery remained in its original position east of the Antietam creek. Union gunners would then have found it difficult, at ranges over 2000 yards, to identify targets and observe the fall of shot. By contrast the Prussian artillery at Froeschwiller, having been criticised for being overly cautious in the Austro-Prussian war of 1866, moved aggressively forward over the Sauerbach stream following their advancing infantry and continuing to provide effective support.
Finally, the Confederates had the good luck that each of their army’s reinforcements arrived on the battlefield just in time to help repel dangerous Union attacks – McLaws’ division in the West Woods, R. H. Anderson’s at the Sunken Road and A. P. Hill’s near the Lower Bridge. When, towards the end of the battle, A.P.Hill’s division arrived on the left flank of the Union IX corps, it had the additional good luck that it encountered an inexperienced Union regiment (16th Connecticut) which failed to rise to the occasion, and achieved tactical surprise through wearing Union clothing scavenged from Harper’s Ferry. The timely and successful flank attack of A.P.Hill’s division spread confusion in the Union ranks, and the psychological setback was sufficient to abort the final Union advance, which might otherwise have cut the Confederate line of retreat. At Froeschwiller French reinforcements marched without urgency, and did not arrive until the battle was lost.
Despite its superior numbers and better weaponry, the Union army failed to win a decisive victory at Antietam whereas the Germans, with a similar numerical superiority, achieved victory at Froeschwiller.
The principal reason for these contrasting results was the relative competence of the opposing commanders in the two battles. At Froeschwiller the French and German commanders (Marshal MacMahon and the Prussian Crown Prince) were both trained and experienced officers with comparable tactical abilities. However at Antietam General Lee managed his defensive battle with great skill while General McClellan proved irresolute and inept; despite his organisational and inspirational talents, he lacked the qualities of generalship needed to fight a battle. If on the 17th September 1862 McClellan had displayed even average competence as a general, or if Lee’s generalship had been any less than outstanding, the Union army would surely have won.
The contrasting results of the two battles illustrate the enduring importance of commander’s making timely and well-directed use of their armies’ reserves, and of potential reinforcements exerting themselves to arrive in time to be effective.
They also illustrate that in 19th and early 20th century warfare the success of an attacking army depended on having artillery which was sufficiently effective against an opposing army deployed for defence. In the American Civil War artillery could not provide decisive support for attacking troops at Antietam or Gettysburg; in the Franco-Prussian War the more-modern German artillery was decisive at Froeschwiller and Sedan against infantry and artillery deployed in the open. A few decades later, artillery was relatively ineffective against entrenched defenders in the Boer War and in the early years of World War I, but helped to achieve breakthroughs at Riga in 1917 and St. Quentin in 1918.
Above all the contrasting results of the battles at Antietam and Froeschwiller demonstrate that the results of battles in this period were essentially unpredictable; the fog of war always prevented perfect knowledge of the strengths of opposing armies and the rapid development of military technology made it difficult to predict the battlefield effectiveness of new weapons. The rival commanders were also aware that the result of a battle would be driven by a sequence of events and decisions which might favour one side or the other (analogous to the dice rolls in some wargames). Amidst these extreme uncertainties, generals needed strong nerves.