That he was esteemed a valiant and skilful officer is apparent from the circumstance, that in 1645 he was appointed general of Prince Maurice's train of artillery, and afterwards held the same rank under Lord Ashley.

The iron districts being still for the most part occupied by the royal armies, our military engineer turned his practical experience to account by directing the forging of drakes[9] of bar-iron, which were found of great use, giving up his own dwelling-house in the city of Worcester for the purpose of carrying on the manufacture of these and other arms.
But Worcester and the western towns fell before the Parliamentarian armies in 1646, and all the iron-works belonging to royalists, from which the principal supplies of arms had been drawn by the King's army, were forthwith destroyed.
Dudley fully shared in the dangers and vicissitudes of that trying period, and bore his part throughout like a valiant soldier.

For two years nothing was heard of him, until in 1648, when the king's party drew together again, and made head in different parts of the country, north and south.

Goring raised his standard in Essex, but was driven by Fairfax into Colchester, where he defended himself for two months.
While the siege was in progress, the royalists determined to make an attempt to raise it.

On this Dud Dudley again made his appearance in the field, and, joining sundry other counties, he proceeded to raise 200 men, mostly at his own charge.