The battle of Trautenau, 27 June 1866, was the only serious Prussian setback during the Austro-Prussian War of 1866, and saw the right-hand column of the eastern wing of the advancing Prussian armies suffer a defeat at the hands of the Austrian 10th Corps.
The Prussians invaded Bohemia in two large groups. In the west the Army of the Elbe and the Prussian 1st Army advanced towards the River Iser. In the east the Prussian 2nd Army, under Crown Prince Friedrich Wilhelm, had the more difficult task. It had to cross the Bohemia Mountains through three passes and establish itself on the Austrian side of the mountains before the Austrian army could concentrate against it. The Austrians were planning to concentrate at Josephstadt on the Elbe, so the main Austrian army was closer to the Crown Prince's army than to the Prussian western armies.
The Crown Prince's army advanced in three columns. On the right (western) flank was the I Corps, under General Von Bonin. In the centre was the Guards Corps and on the left (eastern) flank was V Corps. In theory V Corps had the more difficult task, as their route brought them out closest to the Austrian concentration, but the I Corps performed the worst.
On 27 June Von Bonin ordered his corps to advance in two columns. The right-hand column was to provide the advance guard. The main body of both columns was to advance to Parschnitz, a short distance to the east of Trautenau, and wait there until the advance guard had moved through Trautenau. Unfortunately for the Prussians, the right-hand column, including the advance guard, was held up by slow roads. Von Clausewitz's left-hand column reached Parschnitz at about 8am, but then paused there for two hours waiting for the advance guard. Only then did the advance guard move on.
Trautenau sat on the south bank of the River Aupa. The Prussians approached along a road that ran along the northern side of the river, and crossed it just north of the town. The town was overlooked by three hills - the Galgenberg, Kapellenberg and Hopfenberg, all just to the south-east of the town. Roads ran on both sides of these hills, with one running south-east to Alt-Rognitz and one running south to Hohnebruck.
The Prussian delay gave the Austrians time to move troops into the town. First to arrive was Mondl's brigade from the Austrian 10th Corps (General Gablenz). They took up a position in the town and on the hills overlooking it.
The Prussian advance guard quickly captured the bridge, and after some hard fighting pushed the Austrians out of the town. They then discovered that the Austrian possession of the high ground meant that their position was rather vulnerable, while the Austrian Windischgrätz dragoons were waiting outside the town to pounce on any Prussian advance. The Prussian 1st Dragoons were sent to attack the Austrian cavalry and had the best of a minor melee.
Bonin ordered two battalions from the 41st regiment and one company of Jägers (part of the advance guard) to attack up the hill. This was very difficult terrain, and the advance was slow. General Bonin decided to sent another force (variously given as five or eight battalions) to cross the Aupa and attack the right flank of the Austrian position, heading towards the village of Alt-Rognitz. This attack was even slower, and the advance guard reached the top of the hills before the out-flanking attack was complete.
The combined attack ended in success. The Austrians withdrew to Neu-Rognitz, south-west of Alt-Rognitz. By 3pm the Prussians occupied Hohenbruck and Alt-Rognitz, but half of the available troops were withdrawn to Trautenau to prepare for the advance west.
At some time between noon and 1pm a message arrived from the 1st Division of Guards, part of the Prussian central column, offering assistance. With the battle going well, Bonin turned down this offer of assistance.
The Prussians suffered for their over-confidence. General Gablenz, commander of the 10th Austrian Corps, was approaching from the west with his entire corps. At about 3.30pm the Austrians launched a major counterattack. Mondl's brigade attacked towards Hohnebruck and Grivicic's brigade towards Alt-Rognitz. The Prussians were forced to retreat at about 4pm. Prussian reinforcements held up the advance for a time, but the Austrians retook Hohenbruck at around 4.30.
The Prussians now began a full-scale retreat towards Parschnitz. The 43rd Regiment conducted a successful rear-guard action on the hills east of the Trautenau, and held up Wimpfen's brigade for some time. At 6.00 the Austrians threw in Knebel's brigade, and the 43rd Regiment was forced to retreat. The 3rd Regiment of Grenadiers also took part in the rearguard action, but this stage of the Austrian pursuit was well handled, and the Prussians were force to abandon a plan to defend Trautenau. By the end of the retreat Bonin's corps was back where it had started the day. Gablenz himself spent the night at Trautenau.
The battle of Trautenau was one of the few clear-cut Austrian victories of the war, but even here they suffered much heavier casualties than the Austrians.
The Prussians lost 244 killed, 1,008 wounded and 86 missing, a total of 1,338 casualties. The killed and wounded were made up of 25 officers and 365 men.
The Austrians lost nearly 6,000 men (the sources disagree on the exact figures, but they all come to around 190 officers and 5,200 men dead and around 370 prisoners. The total Austrians losses are given as 5,732 to 5,782. The difference is normally credited to the superior firepower of the Prussian breach-loading needle guns when compared to the Austrian muzzle loading guns.
This was only a temporary setback for the Prussians. On the following days the Guards Corps attacked General Gablenz's 10th Corps in a new position south of Trautenau (battle of Soor or Burkersdorf, 28 June 1866). This time the Prussians were victorious, and the Austrians were forced to retreat west. On the following day the Prussian Guards captured Königinhof, and with it gained a foothold across the Elbe.