On 18 February 1808, Habert won promotion to general of brigade and was granted 4,000 francs worth of annual rent from property in the Kingdom of Westphalia.
Transferred to Spain, he served as a brigade commander in the division of Pierre Hugues Victoire Merle for three weeks before being reassigned to Jean-Antoine Verdier's division in mid-June.
Both divisions formed part of Jean-Baptiste Bessières army corps.
During this period, from 15 June to 14 August, the French waged the unsuccessful First Siege of Zaragoza.
During the siege, Habert led an independent 3,104-man brigade that consisted of the 1st and 2nd Battalions each of the 1st Legion of the Vistula (1,243 men) and the 1st Supplementary Regiment of the Reserve Legion (1,030 men), the 4th Battalion of the 15th Line Infantry Regiment (411 men), and the 3rd Battalion of the 47th Line Infantry Regiment (420 men).

From August, he served in Charles Louis Dieudonné Grandjean's division.
By early November he transferred again to lead the 2nd Brigade of Maurice Mathieu's division in Marshal Bon-Adrien Jeannot de Moncey's III Corps.
On 23 November, Mathieu's division fought in the French victory at the Battle of Tudela.
From 19 December 1808 to 20 February 1809, the III Corps participated in the Second Siege of Zaragoza.
In this bloodbath, 18,000 Spaniards died of battle injuries or sickness.
French losses were also staggering, with 4,000 killed in battle plus an additional 6,000 succumbing to disease.
The III Corps, now led by Jean-Andoche Junot easily overran the Ebro valley after the fall of Saragossa.
However, Spanish guerillas and regulars were soon active again.
As war with Austria threatened, Napoleon withdrew large forces from Spain, leaving Junot only 15,000 troops to occupy the province of Aragon.

In May, Habert received a rude introduction to guerilla warfare when Colonel Perena led his militia in chasing out the French garrison of Monzón.
Desiring to recapture the town, Habert sent a force consisting of about 1,000 men from his elite companies plus some cuirassiers across the Cinca River downstream from Monzón.
However, the river flooded without warning, trapping his detachment on the far bank.
With the rest of his troops Habert attempted to cross at Monzón itself, but Perena's men repelled all his assaults on 16 May. The cavalry swam their horses across the river and escaped.
But the isolated foot soldiers ran out of ammunition and were forced to surrender on 19 May as Habert watched helplessly.
In this action, Habert commanded Junot's 1st Division of 9,000 troops and 12 guns, with two squadrons of the 13th Cuirassier Regiment attached.
Perena's estimated 10,000 Miqueletes captured three voltiguer (light) companies of the 14th Line Infantry Regiment, the grenadier and voltiguer companies of the 116th Line Infantry Regiment, and possibly other units.

 
On the day that Habert's elite companies laid down their arms, Louis-Gabriel Suchet arrived to replace Junot in command.
The Battle of Alcañiz on 23 May 1809, Suchet's first action in independent command, was a French defeat at the hands of Joaquín Blake y Joyes.
Before the battle, Habert was ordered to join Suchet.
In the action, the 1st Division was led by Anne-Gilbert Laval while the 2nd Division was commanded by Louis François Félix Musnier.
Habert is not listed in the order of battle.

Soon, Blake was menacing Zaragoza and Suchet led his rallied troops out to fight the Battle of María on 15 June.
In this action, the French corps commander detached Laval to protect Saragossa, while Habert led the remainder of the 1st Division.
Knowing 3,000 reinforcements were due to arrive, Suchet maintained the defensive all day.
When the hoped-for troops showed up at 4:00 PM, the French general hurled Habert's infantry and Pierre Watier's cavalry at Blake's right wing.
Under the double attack, the Spanish line caved in.
The French inflicted 1,000 killed and 3,000 to 4,000 wounded on their opponents while suffering 700 to 800 killed and wounded.
Two days later, Blake stood to fight again at Belchite.
Suchet sent Musnier to a
On 18 February 1808, Habert won promotion to general of brigade and was granted 4,000 francs worth of annual rent from property in the Kingdom of Westphalia. Transferred to Spain, he served as a brigade commander in the division of Pierre Hugues Victoire Merle for three weeks before being reassigned to Jean-Antoine Verdier's division in mid-June. Both divisions formed part of Jean-Baptiste Bessières army corps. During this period, from 15 June to 14 August, the French waged the unsuccessful First Siege of Zaragoza. During the siege, Habert led an independent 3,104-man brigade that consisted of the 1st and 2nd Battalions each of the 1st Legion of the Vistula (1,243 men) and the 1st Supplementary Regiment of the Reserve Legion (1,030 men), the 4th Battalion of the 15th Line Infantry Regiment (411 men), and the 3rd Battalion of the 47th Line Infantry Regiment (420 men).
From August, he served in Charles Louis Dieudonné Grandjean's division. By early November he transferred again to lead the 2nd Brigade of Maurice Mathieu's division in Marshal Bon-Adrien Jeannot de Moncey's III Corps. On 23 November, Mathieu's division fought in the French victory at the Battle of Tudela. From 19 December 1808 to 20 February 1809, the III Corps participated in the Second Siege of Zaragoza. In this bloodbath, 18,000 Spaniards died of battle injuries or sickness. French losses were also staggering, with 4,000 killed in battle plus an additional 6,000 succumbing to disease. The III Corps, now led by Jean-Andoche Junot easily overran the Ebro valley after the fall of Saragossa. However, Spanish guerillas and regulars were soon active again. As war with Austria threatened, Napoleon withdrew large forces from Spain, leaving Junot only 15,000 troops to occupy the province of Aragon.
In May, Habert received a rude introduction to guerilla warfare when Colonel Perena led his militia in chasing out the French garrison of Monzón. Desiring to recapture the town, Habert sent a force consisting of about 1,000 men from his elite companies plus some cuirassiers across the Cinca River downstream from Monzón. However, the river flooded without warning, trapping his detachment on the far bank. With the rest of his troops Habert attempted to cross at Monzón itself, but Perena's men repelled all his assaults on 16 May. The cavalry swam their horses across the river and escaped. But the isolated foot soldiers ran out of ammunition and were forced to surrender on 19 May as Habert watched helplessly. In this action, Habert commanded Junot's 1st Division of 9,000 troops and 12 guns, with two squadrons of the 13th Cuirassier Regiment attached. Perena's estimated 10,000 Miqueletes captured three voltiguer (light) companies of the 14th Line Infantry Regiment, the grenadier and voltiguer companies of the 116th Line Infantry Regiment, and possibly other units.
 
On the day that Habert's elite companies laid down their arms, Louis-Gabriel Suchet arrived to replace Junot in command. The Battle of Alcañiz on 23 May 1809, Suchet's first action in independent command, was a French defeat at the hands of Joaquín Blake y Joyes. Before the battle, Habert was ordered to join Suchet. In the action, the 1st Division was led by Anne-Gilbert Laval while the 2nd Division was commanded by Louis François Félix Musnier. Habert is not listed in the order of battle.
Soon, Blake was menacing Zaragoza and Suchet led his rallied troops out to fight the Battle of María on 15 June. In this action, the French corps commander detached Laval to protect Saragossa, while Habert led the remainder of the 1st Division. Knowing 3,000 reinforcements were due to arrive, Suchet maintained the defensive all day. When the hoped-for troops showed up at 4:00 PM, the French general hurled Habert's infantry and Pierre Watier's cavalry at Blake's right wing. Under the double attack, the Spanish line caved in. The French inflicted 1,000 killed and 3,000 to 4,000 wounded on their opponents while suffering 700 to 800 killed and wounded. Two days later, Blake stood to fight again at Belchite. Suchet sent Musnier to a
Pierre-Joseph Habert