The siege of Mequinenza of 15 May-18 June 1810 saw the French capture the strategically important town, at the highest navigable point on the Ebro. The small town of Mequinenza is located at the junction of the Ebro and the Siegre. The town itself was built by the river and was protected by a weak wall, but it had a strong castle, built 500 feet above the river at the end of a spur of the Sierra de Montenegra. The castle was not integrated into the defences of the town, but unless the French could capture both they would be unable to use the Ebro. The town was defended by 1,000 men under Colonel Carbon.
The siege was conducted by Marshal Suchet’s Army of Aragon. On 14 May Suchet had taken the surrender of Lerida, after a month long siege, and on the following day had sent the first troops south to Mequinenza. His engineers soon realised that the only way to attack the castle would be to build a new road onto the top of the Sierra de Montenegra. This five mile long road was complete by 1 June. On 5 June the French successfully stormed the town, leaving Carbon isolated in the castle.
Although the road onto the Sierra de Montenegra had been completed on 1 June, it would seem to have taken another ten days to build three gun batteries on the heights and to bring guns into place. The bombardment is said to have lasted for eight days. By the end of that bombardment the walls facing the French trenches were in ruins, and with no prospect of successfully defending the castle, on 18 June Carbon surrendered.
Although the French had captured the town and castle, Carbon had made sure that nine of the eleven river boats in the town escaped. Despite this Suchet was able to use Mequinenza as his artillery depot during his preparations for the siege of Tortosa, before floating his heavy guns down the Ebro.