On Queen Elizabeth's accession in November 1558, Dudley was appointed Master of the Ordnance, in which capacity he was to unofficially assist William the Silent in his struggle against Spain by delivering English weaponry.

Dudley, who had acted honorably throughout, returned with a severe leg wound which was to hinder his further career and ultimately led to his death 27 years later.

Like Robert Dudley, Ambrose was a major patron of the Elizabethan Puritan movement and supported non-conforming preachers in their struggle with the Church authorities.

[1] Dudley soon married for the second time: Elizabeth, Lady Tailboys (or Talboys, 1520–1563[1]), who was a baroness in her own right with large possessions in Lincolnshire and Yorkshire.

[11] After the natural death of John, the eldest brother, in October 1554, Ambrose Dudley was the family's heir; he remained longest in the Tower, being released late in 1554 after a plea by his wife, Lady Tailboys.

[12] On the whole, the brothers' release was brought about by their mother and their brother-in-law Henry Sidney, who successfully lobbied the Spanish nobles around Queen Mary I's new husband and co-ruler, Philip of Spain.

[13] Out of prison, in December 1554 or January 1555, Ambrose and Robert Dudley took part in one of several tournaments held by Philip to celebrate Anglo-Spanish friendship.

Ambrose Dudley received the post of Master of the Ordnance, though he pressed his influential brother to delay the appointment somewhat, so that he could not be held accountable for his predecessor's embezzlement of funds.

[1] Yet on 25 and 26 December 1561, Ambrose Dudley was created Baron Lisle and Earl of Warwick, and the next year received a large portion of the lands confiscated from the Duke of Northumberland.

[21] Like their father, Ambrose and Robert Dudley adopted the bear and ragged staff, the heraldic device of the medieval Earls of Warwick.

These were in possession of Le Havre, which was besieged by the Catholic Duke of Guise, and offered it to the English in return for military help—later, they promised, they would exchange it for Calais, which England had lost to France only in 1558.

[1] Elizabeth soon made it clear that she did not wish his army to engage in any active support for the Huguenot side, the purpose of the English contribution remaining somewhat obscure.

[26] Politically, the expedition had been a disaster, yet Warwick gained recognition for his leadership since morale had been high and the civilian population had been treated with unusual respect.

[1] As Master of the Ordnance, Warwick presided over an increasingly important government department, which centrally managed the storage and commissioning of the state's artillery, munitions, and small arms.

[1] At the 1587 trial of Mary Stuart, he acted as a commissioner and was asked by the Scottish Queen to plead for her with his brother, the absent Earl of Leicester.

"[35] Ambrose Dudley also helped the preacher John Field when he got into trouble over a subversive book he had published in 1565; and when he was imprisoned in 1572, Leicester and Warwick worked his transfer into comfortable confinement in a London alderman's house before he was released altogether by his patrons' means.

[36] Like his brother, Ambrose Dudley invested in exploration and privateering voyages; in Martin Frobisher's 1576 search for the Northwest Passage, he was the principal patron, although he contributed only the relatively modest sum of £50.

[43] Ambrose's childlessness deeply concerned the widowed Robert Dudley, who for many years dared not to remarry for fear of the Queen's displeasure,[44] and eventually died without direct heirs himself in September 1588.

He also took care of his deceased brother's illegitimate teenage son Robert, who was his godson and whom Leicester had willed to inherit after Warwick's death.

[45] At the end of January 1590, he finally had his gangrenous leg amputated; as a consequence, he died at Bedford House in the Strand, London, on 21 February.

[27] Ambrose Dudley entered tradition as the "Good Earl of Warwick"; this probably came about through his quiet life style, which contrasted with the colourful persona of his brother, the Queen's favourite.