Suchet invaded the province of Valencia in September 1811. He tried to quickly seize the Sagunto Castle, but its garrison repulsed two attacks and the French-Allied army was forced to lay siege to the ancient fortress. When Blake's army advanced from Valencia, Suchet posted his smaller army to resist the Spanish. Blake's attack on Suchet's right flank went awry and soon the poorly trained Spanish troops were fleeing. The Spanish troops attacking Suchet's left flank were made of sterner stuff, however, and the contest there was more severe. Finally, the French-Allied troops gained the upper hand and put the entire Spanish army to flight. Blake's soldiers limped back to Valencia where they tried to put that city's defences in order.
Spanish losses numbered 6,000 killed and wounded, plus several hundred prisoners, some cannons, and four colors. The 2,500-man garrison of Castle Saguntum, led by Brigadier General Luis Maria Andriani, fought a valiant defense against superior French forces, gaining invaluable time for General Blake to prepare for his climatic battle with Suchet. Despite Andriani's extraordinary efforts at withstanding an unrelenting French siege lasting almost 30 days, and having run out of food and ammunition, he had no choice but to surrender the garrison after watching Suchet defeat and scatter Blake's relief army. Suchet lost only 1,000 killed and wounded, but apart from the seizing the castle, he was unable to immediately capitalize on his victory. His army was too small to capture Valencia, especially after his battle losses at Castle Saguntum and the need to garrison the captured castle with French troops. For several weeks the French-Allies paused to wait for reinforcements before launching the next phase of their offensive.