In 1813 Major-General Pack had been appointed a Knight Commander of the Portuguese Order of the Tower and Sword, and on the 2d of January 1815 was nominated a Knight Commander of the Order of the Bath. He received a cross and seven clasps for the following actions, at all of which he commanded troops, and was personally engaged: Roleia, Vimiera, Corunna, Busaco, siege of Ciudad Rodrigo, Salamanca, Vittoria, Pyrenees, Nivelle, Nive, Orthes, and Toulouse. Sir Denis Pack had received eight wounds, six of them rather severe ones; had been frequently struck by shot, and had several horses killed and wounded under him.
In March 1815 Europe was astounded by the return of Napoleon to Paris. The allied powers, however, refused to recognize his sovereignty, and determined on his dethronement. A large army proceeded to Flanders under Field Marshal the Duke of Wellington, and Major-General Sir Denis Pack was placed in command of a brigade. The campaign was as brief as it was glorious. On the 16th of June, Napoleon, after having made one of his rapid movements, attacked the Anglo-Belgian troops at Quatre Bras, in which the fifth division under Lieut.-General Sir Thomas Picton, of which Major-General Sir Denis Pack’s brigade formed part, was engaged. Then followed the movement on the 17th to Waterloo, where, on the 18th of June, was fought that memorable battle in which the sun of Napoleon set for ever, and the result of which gave to Europe a lengthened period of tranquillity. These arduous conflicts afforded Major-General Sir Denis Pack several opportunities for distinguishing himself, and adding to his former honors.
Sir Denis Pack had the honor to receive the thanks of both Houses of Parliament on six different occasions; namely, for his conduct in the battles of Roleia and Vimiera; for the siege of Ciudad Rodrigo; and for the battles of Salamanca, Vittoria, Orthes, and Waterloo.
On the 8th of January 1816 Major-General Sir Denis Pack was appointed colonel of the York chasseurs, which corps was subsequently disbanded. On the 12th of August 1819 he was appointed lieut.-governor of Plymouth, and to the command of the troops in the western district, and on the 9th of September 1822 he was appointed colonel of the eighty-fourth regiment. The decease of Major-General Sir Denis Pack occurred on the 24th of July 1823, at which period he held the command of the troops in the western district of Great Britain, and the lieut.-governorship of Plymouth.