At the start of the War of the Fifth Coalition, d'Aspré led a brigade in Michael von Kienmayer's small II Reserve Armeekorps consisting of the Puteani, Brezeczinsky, Scovaud, Kirchenbetter, and Scharlach grenadier battalions, plus a battery of eight 6-pounder cannons.
In the Battle of Abensberg on 20 April 1809, Archduke Louis of Austria tried unsuccessfully to defend the line of the Abens River.
During the morning, Louis called up Kienmayer's corps from Ludmannsdorf to support Joseph Radetzky von Radetz's left flank brigade near Siegenburg.
During the afternoon, d'Aspré's grenadiers supported Radetzky as he fell back toward Pfeffenhausen.
At 11:00 PM that night, Bavarian pursuers aggressively crossed the Große Laber stream and attacked.
Radetzky borrowed one of d'Aspré's grenadier battalions and held the Hornbach hill south of Pfeffenhausen until the early morning hours.

On 21 April, Napoleon attacked Johann von Hiller in the Battle of Landshut but the Austrians managed to avoid being trapped.
However, Hiller's left wing lost an estimated 9,000 casualties during the day.
Three of d'Aspré's grenadier battalions formed the Austrian rear guard as they retreated to Neumarkt-Sankt Veit.
D'Aspre was present at the Battle of Neumarkt-Sankt Veit on 24 April, when Hiller lashed out at his Bavarian and French pursuers.
Kienmayer's force retreated through Braunau am Inn on 26 April.
D'Aspré missed the hard-fought Battle of Ebelsberg on 3 May. Hiller unwisely sent Kienmayer's troops to Asten, even as the French were in the process of driving in his rear guards.
Nevertheless, d'Aspré's promotion to Feldmarschall-Leutnant came through the next day.

On 8 May, most of Hiller's wing, including Kienmayer's corps, crossed to the north bank of the Danube at Mautern an der Donau.
Within a short time, d'Aspré's grenadiers crossed to the south bank again to assist in Archduke Maximilian of Austria-Este's short-lived defence of Vienna.
Other defending forces were landwehr under Andreas O'Reilly von Ballinlough, a division led by Josef von Dedovich, and a brigade co-commanded by Armand von Nordmann and Joseph, Baron von Mesko de Felsö-Kubiny.
At 3:00 AM on 12 April, d'Aspré led his five battalions in an attack on the French positions at the Lusthaus on Prater Island.
The attack was repulsed by the defenders, but its real purpose was to cover the Austrian retreat to the north bank of the Danube, which was successfully carried out.

In mid-May, Archduke Charles, Duke of Teschen merged the II Reserve Armeekorps into the I Reserve Armeekorps under the leadership of Johann I Joseph, Prince of Liechtenstein.
In the new organization, d'Aspré and Johann Nepomuk von Prochaska became the two infantry division commanders.
D'Aspré's division comprised the five battalions from his former brigade plus the Bissingen, Oklopsin, and Mayblümel grenadier battalions.
The 5,362 elite infantry were divided into two 4-battalion brigades under Franz Mauroy de Merville and Anton von Hammer, and included a brigade battery of six 6-pounder cannons.

 
On 21 May, the first day of the Battle of Aspern-Essling, the grenadier reserve was not committed to combat.
The next day, Napoleon tried to break out of the narrow bridgehead by sending Marshal Jean Lannes with three divisions to assault the weak Austrian centre.
In the crisis, Archduke Charles moved d'Aspré's and Prochaska's grenadier divisions (under Kienmayer) to block Lannes.
When the troops showed unsteadiness, Charles personally waved the colours of the grenadiers of the Zach Infantry Regiment Nr.
15 to rally his troops.
This greatly heartened the defenders, and the French assault was defeated when reinforcements arrived from the right and left flanks.
In the afternoon, Charles ordered Merville's brigade from d'Aspré's division to attack Essling, which had held out against repeated assaults.
The grenadiers routed the French from the village, except for the fortress-like granary which held out.
Later, five battalions of the Imperial Guard recaptured Essling.

On 24 May, the emperor appointed d'Aspré Proprietor (Inhaber)
At the start of the War of the Fifth Coalition, d'Aspré led a brigade in Michael von Kienmayer's small II Reserve Armeekorps consisting of the Puteani, Brezeczinsky, Scovaud, Kirchenbetter, and Scharlach grenadier battalions, plus a battery of eight 6-pounder cannons. In the Battle of Abensberg on 20 April 1809, Archduke Louis of Austria tried unsuccessfully to defend the line of the Abens River. During the morning, Louis called up Kienmayer's corps from Ludmannsdorf to support Joseph Radetzky von Radetz's left flank brigade near Siegenburg. During the afternoon, d'Aspré's grenadiers supported Radetzky as he fell back toward Pfeffenhausen. At 11:00 PM that night, Bavarian pursuers aggressively crossed the Große Laber stream and attacked. Radetzky borrowed one of d'Aspré's grenadier battalions and held the Hornbach hill south of Pfeffenhausen until the early morning hours.
On 21 April, Napoleon attacked Johann von Hiller in the Battle of Landshut but the Austrians managed to avoid being trapped. However, Hiller's left wing lost an estimated 9,000 casualties during the day. Three of d'Aspré's grenadier battalions formed the Austrian rear guard as they retreated to Neumarkt-Sankt Veit. D'Aspre was present at the Battle of Neumarkt-Sankt Veit on 24 April, when Hiller lashed out at his Bavarian and French pursuers. Kienmayer's force retreated through Braunau am Inn on 26 April. D'Aspré missed the hard-fought Battle of Ebelsberg on 3 May. Hiller unwisely sent Kienmayer's troops to Asten, even as the French were in the process of driving in his rear guards. Nevertheless, d'Aspré's promotion to Feldmarschall-Leutnant came through the next day.
On 8 May, most of Hiller's wing, including Kienmayer's corps, crossed to the north bank of the Danube at Mautern an der Donau. Within a short time, d'Aspré's grenadiers crossed to the south bank again to assist in Archduke Maximilian of Austria-Este's short-lived defence of Vienna. Other defending forces were landwehr under Andreas O'Reilly von Ballinlough, a division led by Josef von Dedovich, and a brigade co-commanded by Armand von Nordmann and Joseph, Baron von Mesko de Felsö-Kubiny. At 3:00 AM on 12 April, d'Aspré led his five battalions in an attack on the French positions at the Lusthaus on Prater Island. The attack was repulsed by the defenders, but its real purpose was to cover the Austrian retreat to the north bank of the Danube, which was successfully carried out.
In mid-May, Archduke Charles, Duke of Teschen merged the II Reserve Armeekorps into the I Reserve Armeekorps under the leadership of Johann I Joseph, Prince of Liechtenstein. In the new organization, d'Aspré and Johann Nepomuk von Prochaska became the two infantry division commanders. D'Aspré's division comprised the five battalions from his former brigade plus the Bissingen, Oklopsin, and Mayblümel grenadier battalions. The 5,362 elite infantry were divided into two 4-battalion brigades under Franz Mauroy de Merville and Anton von Hammer, and included a brigade battery of six 6-pounder cannons.
 
On 21 May, the first day of the Battle of Aspern-Essling, the grenadier reserve was not committed to combat. The next day, Napoleon tried to break out of the narrow bridgehead by sending Marshal Jean Lannes with three divisions to assault the weak Austrian centre. In the crisis, Archduke Charles moved d'Aspré's and Prochaska's grenadier divisions (under Kienmayer) to block Lannes. When the troops showed unsteadiness, Charles personally waved the colours of the grenadiers of the Zach Infantry Regiment Nr. 15 to rally his troops. This greatly heartened the defenders, and the French assault was defeated when reinforcements arrived from the right and left flanks. In the afternoon, Charles ordered Merville's brigade from d'Aspré's division to attack Essling, which had held out against repeated assaults. The grenadiers routed the French from the village, except for the fortress-like granary which held out. Later, five battalions of the Imperial Guard recaptured Essling.
On 24 May, the emperor appointed d'Aspré Proprietor (Inhaber) 
Konstantin Ghilian Karl d'Aspré