The Archbishopric of Mainz suffered heavily in the late 18th century.
Following the invasion by French revolutionary troops in 1792, Mainz came under attack from Prussian troops in 1793 in the siege that led to the end of the Republic of Mainz.
This attack damaged large portions of the cathedral, particularly the east wing, the cloister, and the Liebfrauenkirche, which was demolished in 1803 (the year after Mainz lost its archbishopric and became a regular diocese).
The cathedral was used as an army camp for several years, and therefore large amounts of the cathedral's artefacts were sold, the wooden interior was burned for heat.

Bishop Joseph Ludwig Colmar (1802–1818), with support from Napoleon, set into motion restoration efforts.
These efforts were interrupted by quartering needs for the French Army in 1813, and the cathedral was used as a church in 1814 for the first time in eleven years.
By 1831, the reparations had been for the most part completed.
The major change to the building was an iron cupola on the main eastern tower built by architect Georg Moller.
But this cupola was removed in 1870 because it was too heavy.

After that, Pierre Cuypers undertook a lengthy restoration work.
The support pillar in the eastern cross-tower was removed, as the heavy belfry no longer stood.
The crypt in the eastern chancel was rebuilt, but not to the original specifications of the one built by Henry IV.
At the conclusion of these reconstructions, a neo-Romanesque tower was erected in place of the eastern cross-tower in 1875.

At this time the cathedral was once again repainted.
Large and colorful Nazarene movement murals, including some by Philipp Veit, were painted to decorate the inside of the cathedral.
The Archbishopric of Mainz suffered heavily in the late 18th century. Following the invasion by French revolutionary troops in 1792, Mainz came under attack from Prussian troops in 1793 in the siege that led to the end of the Republic of Mainz. This attack damaged large portions of the cathedral, particularly the east wing, the cloister, and the Liebfrauenkirche, which was demolished in 1803 (the year after Mainz lost its archbishopric and became a regular diocese). The cathedral was used as an army camp for several years, and therefore large amounts of the cathedral's artefacts were sold, the wooden interior was burned for heat.
Bishop Joseph Ludwig Colmar (1802–1818), with support from Napoleon, set into motion restoration efforts. These efforts were interrupted by quartering needs for the French Army in 1813, and the cathedral was used as a church in 1814 for the first time in eleven years. By 1831, the reparations had been for the most part completed. The major change to the building was an iron cupola on the main eastern tower built by architect Georg Moller. But this cupola was removed in 1870 because it was too heavy.
After that, Pierre Cuypers undertook a lengthy restoration work. The support pillar in the eastern cross-tower was removed, as the heavy belfry no longer stood. The crypt in the eastern chancel was rebuilt, but not to the original specifications of the one built by Henry IV. At the conclusion of these reconstructions, a neo-Romanesque tower was erected in place of the eastern cross-tower in 1875.
At this time the cathedral was once again repainted. Large and colorful Nazarene movement murals, including some by Philipp Veit, were painted to decorate the inside of the cathedral.
Mainz Cathedral