Johann Gabriel Chasteler de Courcelles (1763-1825) was an Austrian general who served as a engineer, a staff officer and a corps commander.
Chasteler was born in Mons, Belgium, in 1763, at a time when the area was part of the vast Habsburg Empire. He joined the army in 1776, as a cadet in Infantry Regiment Lothringen, before attending the Netherlands engineer school.
Chasteler fought in the Austro-Turkish War of 1788-91. His right leg was badly damaged during the siege of Chotym, and he was awarded the Maria Theresa Order for his role in the fighting. After the end of the Austro-Turkish War he was promoted to Oberstleutnant, given command of the Netherlands ceremonial guard (the Arcieren Guard), and made an Imperial Chamberlain.
After the outbreak of the Revolutionary Wars, Chasteler served with the Engineers. He took command of the restoration of the fortress at Namur, and then took part in the sieges of Landrecies and Lüttich.
In 1795 he helped General Clerfayt raise the siege of Mainz (14 December 1794-29 October 1795), and was promoted to the rank of Oberst on the army staff. He was promoted again, to Major General, in 1797.
In 1799 Chasteler was appointed chief-of-staff to the Russian Marshal Suvorov during the campaign in which the Austrians and Russians undid most of Napoleon's famous conquests in Italy. Chasteler planned the operations to cross the Adda (battle of Cassano, 26-28 April 1799), which allowed the Allies to recapture Milan.
Chasteler develops the plan for the advance into Piedmont, but this was a fairly typical flawed Austrian plan, involving too many columns operating too far apart. Two were to cross the Po between the Adda and the Ticino, a third to the east of Valenza and other columns were to support the attack and to protect against the French army of Naples, advancing from the south. The advance made steady progress, but wasn't without problems. On 12 May Roesenberg was defeated when attempting to cross the Po east of Valenza. On 16 May Victor attacked and pushed back the Allied outposts before retreating to Alessandria after running into the main Allied forces (Battle of San Giuliano, 16 May 1799).
The various French armies in Italy soon threatened to unite. Suvorov decided to attack Macdonald's Army of Rome before he could join with Moreau's army coming from Genoa. Chasteler took part in the resulting battle of the Trebbia (17-19 June 1799), a major Allied victory that left Moreau isolated. Chasteler took part in the siege of Alessandria, where he was badly wounded for a second time.
Chasteler was given the Commander Cross of the Maria Theresa Order for his role on the Adda and at the Trebbia.
In 1800 Chasteler was appointed deputy chief-of-staff in Kray's army in Germany.
After defending the Scharnitz Pass in the Tyrol he was promoted to Feldmarschalleutnant (Lieutenant-General).
He returned to the Tyrol in 1805 as command of the right wing in the army of the Archduke John during the War of the Third Coalition. Once again he was given the task of defending mountain passes.
In 1809 Chasteler served under the Archduke John in Italy. He commanded VIII Corps for a period, and then returned to the Tyrol, but suffered a heavy defeat at Wörgl (13 May 1809) at the hands of a Bavarian force under Marshal Lefebvre.
After the end of the war he was appointed military Commandant in Silesia.
In 1813 Chasteler served under Schwarzenberg in the Autumn Campaign of the War of Liberation. He directed the defences of Prague, although Napoleon never actually made very far into Bohemia, so these weren't tested. He then joined the field army, and commanded part of the Allied left at the battle of Dresden. His troops arrived at 8am on the morning of the first day of the battle (26 August), and he was posted on the right bank of the Weisseritz, facing Plauen. His task was to capture Plauen and then cover the advance of Bianchi on the left bank of the river. In the event his column made little progress, and neither did Bianchi. On the second day he was unable to intervene as Napoleon defeated the far left wing of the Allied army, on the opposite bank of the Weisseritz. He also fought at Kulm, where Vandamme's corps was isolated and forced to surrender, largely negating the results of Napoleon's victory at Dresden.
He was promoted to Feldzeugmeister (General of Infantry) and given command of the fortress at Theresienstadt. After the battle of Leipzig he took over command of Klenau's Corps, and took part in the later stages of the Siege of Dresden (arriving after 17 October).
After the end of the Napoleonic Wars he was responsible for the restoration of the defences of Venice, which was returned to Austrian control after eight years under French control (as part of the Kingdom of Italy).