On the 6th April, he harassed the French, then retreating from Tarragona towards Barcelona; and after retiring from Vich with an army discomfited by only 5000 Frenchmen, with the same discomfited men he baffled Augereau, who led 20,000 bayonets; forced him to abandon Lower Catalonia, and to retreat in disgrace to Gerona, where Marshal Macdonald, a Scotsman, was sent by Napoleon to succeed him. During the investment of Hostalric by the French, Henry O'Donnel collected many convoys for its relief; he attacked the blockade at several points with the Miguelets, and particularly distinguished himself in a noble and dashing attempt to relieve the brave Julian Estrada, on the night of the 12th May, when this strong citadel fell. During the siege of Lerida by Suchet, O'Donnel collected two divisions of 4000 each; with these and 600 cavalry he skilfully passed the defile of Momblanch, and fought the contest of Margalef, where his troops were defeated; but he rallied, and led them again upon the columns of the Duc d'Albufera. The struggle was terrible; but he was forced to retreat through the passes, leaving one general, eight colonels, 5000 men, and three guns in the hands of the foe. His force was now 1400 strong, well supplied by the active Miguelets; and by the bravery of his soldiers and his own unwearying zeal he long prevented the siege of Tortoza, and found full employment for the enemy during the remainder of the year. "After the battle of Margalef, Henry O'Donnel re-united his forces, and being of a stern, unyielding disposition, not only repressed the discontents occasioned by that defeat, but forced the reluctant (and lawless) Miguelets to supply his ranks and submit to discipline." Thus, in July he had twenty-two thousand men when Marshals Macdonald and Suchet combined to crush him, and when Napoleon's order to invest Tortoza arrived. On this O'Donnel, after making a skilful feint towards Trivisa, suddenly threw himself with ten thousand men into the fated city, from whence, upon the noon of the 3rd July, he fell furiously upon the French entrenchments, and made a fearful slaughter of the troops of Laval. After this he retired to Tarragona. Having cut off Macdonald's communication with the walled city of Ampurias, he now conceived and executed the most skilful and vigorous plan which had yet graced the Spanish arms.