One of the greatest heroes of the Par. War. Led the Forlorn Hope on two successive occasions during the siege of Badajoz, in 1811, when Fort San Christoval was assaulted by the British. The second assault, on the night of 9th June, is graphically described in _Reminiscences of a Subaltern_:—“At ten o’clock at night, 200 men moved forward to the assault, Dyas leading the advance. He made a circuit until he came exactly opposite to the breach instead of entering the ditch as before; a sheep-path, which he remembered in the evening while he and Major MacGeechy made their observations, served to guide them to the part of the glacis in front of the breach. Arrived at this spot, the detachment descended the ditch, and found themselves at the foot of the breach; but here an unlooked-for event stopped their further progress, and would have been in itself sufficient to have caused the failure of the attack. The ladders were entrusted to a party composed of a foreign corps in our pay, called ‘the Chasseurs Britanniques’; these men, the moment they reached the glacis, glad to rid themselves of their load, flung the ladders into the ditch, instead of sliding them between the palisadoes; they fell across them, and so stuck fast, and being made of heavy green wood, it was next to impossible to _move_, much less place them upright against the breach, and almost all the storming party were massacred in the attempt. Placed in a situation so frightful, it required a man of the most determined character to continue the attack. Every officer of the detachment had fallen, Major MacGeechy one of the first; and at this moment Dyas and about five-and-twenty men were all that remained of the 200. Undismayed by these circumstances, the soldiers persevered, and Dyas, although wounded and bleeding, succeeded in disentangling one ladder, and placing it against what was considered to be the breach, it was speedily mounted, but upon arriving at the top of the ladder, instead of the _breach_, it was found to be a _stone wall_ that had been constructed in the night, and which completely cut off all communication between the ditch and the bastion, so that when the men reached the top of this wall, they were, in effect, as far from the breach as if they had been in their own batteries. From this faithful detail it is evident that the soldiers did as much as possible to ensure success, and that failure was owing to a combination of untoward circumstances over which the troops had no control. Nineteen men were all that escaped.” The gallantry of Ensign Joseph Dyas was proclaimed to the world in Wellington’s account of the two assaults of San Christoval, but for all that a grateful War Office allowed him to remain a subaltern for ten years longer!