During the 1570s Leicester built a special relationship with Prince William of Orange, who held him in high esteem.
The Earl became generally popular in the Netherlands.
Since 1577 he pressed for an English military expedition, led by himself (as the Dutch strongly wished) to succour the rebels.
In 1584 the Prince of Orange was murdered, political chaos ensued, and in August 1585 Antwerp fell to the Duke of Parma.
An English intervention became inevitable; it was decided that Leicester would go to the Netherlands and "be their chief as heretofore was treated of", as he phrased it in August 1585.
He was alluding to the recently signed Treaty of Nonsuch in which his position and authority as "governor-general" of the Netherlands had only been vaguely defined.
The Earl prepared himself for "God's cause and her Majesty's" by recruiting the expedition's cavalry from his retainers and friends, and by mortgaging his estate to the sum of £25,000.

On Thursday 9 December 1585, the Earl of Leicester set sail for the Low Countries from Harwich and landed after a swift crossing of less than 24 hours, the fleet anchored at Flushing (Vlissingen).
At the end of December 1585 Leicester was received in the Netherlands, according to one correspondent, in the manner of a second Charles V; a Dutch town official already noted in his minute-book that the Earl was going to have "absolute power and authority".
After a progress through several cities and so many festivals he arrived in The Hague, where on 1 January 1586 he was urged to accept the title governor-general by the States General of the United Provinces.
Leicester wrote to Burghley and Walsingham, explaining why he believed the Dutch importunities should be answered favourably.
He accepted his elevation on 25 January, having not yet received any communications from England due to constant adverse winds.

The Earl had now "the rule and government general" with a Council of State to support him (the members of which he nominated himself).
He remained a subject of Elizabeth, making it possible to contend that she was now sovereign over the Netherlands.
According to Leicester, this was what the Dutch desired.
From the start such a position for him had been implied in the Dutch propositions to the English, and in their instructions to Leicester; and it was consistent with the Dutch understanding of the Treaty of Nonsuch.
The English queen, however, in her instructions to Leicester, had expressly declined to accept offers of sovereignty from the United Provinces while still demanding of the States to follow the "advice" of her lieutenant-general in matters of government.
Her ministers on both sides of the Channel hoped she would accept the situation as a fait accompli and could even be persuaded to add the rebellious provinces to her possessions.
Instead her fury knew no bounds and Elizabeth sent Sir Thomas Heneage to read out her letters of disapproval before the States General, Leicester having to stand nearby.
Elizabeth's "commandment" was that the Governor-General immediately resign his post in a formal ceremony in the same place where he had taken it.
After much pleading with her and protestations by the Dutch, it was postulated that the governor-generalship had been bestowed not by any sovereign, but by the States General and thereby by the people.
The damage was done, however: "My credit hath been cracked ever since her Majesty sent Sir Thomas Heneage hither", Leicester recapitulated in October 1586.

Elizabeth demanded of her Lieutenant-General to refrain at all cost from any decisive action with Parma, which was the opposite of what Leicester wished and what the Dutch expected of him.
After some initial successes, the unexpected surrender of the strategically important town of Grave was a serious blow to English morale.
Leicester's fury turned on the town's governor, Baron Hemart, whom he had executed despite all pleadings.
The Dutch nobility were astonished: even the Prince of Orange would not have dared such an outrage, Leicester was warned; but, he wrote, he would not be intimidate
During the 1570s Leicester built a special relationship with Prince William of Orange, who held him in high esteem. The Earl became generally popular in the Netherlands. Since 1577 he pressed for an English military expedition, led by himself (as the Dutch strongly wished) to succour the rebels. In 1584 the Prince of Orange was murdered, political chaos ensued, and in August 1585 Antwerp fell to the Duke of Parma. An English intervention became inevitable; it was decided that Leicester would go to the Netherlands and "be their chief as heretofore was treated of", as he phrased it in August 1585. He was alluding to the recently signed Treaty of Nonsuch in which his position and authority as "governor-general" of the Netherlands had only been vaguely defined. The Earl prepared himself for "God's cause and her Majesty's" by recruiting the expedition's cavalry from his retainers and friends, and by mortgaging his estate to the sum of £25,000.
On Thursday 9 December 1585, the Earl of Leicester set sail for the Low Countries from Harwich and landed after a swift crossing of less than 24 hours, the fleet anchored at Flushing (Vlissingen). At the end of December 1585 Leicester was received in the Netherlands, according to one correspondent, in the manner of a second Charles V; a Dutch town official already noted in his minute-book that the Earl was going to have "absolute power and authority". After a progress through several cities and so many festivals he arrived in The Hague, where on 1 January 1586 he was urged to accept the title governor-general by the States General of the United Provinces. Leicester wrote to Burghley and Walsingham, explaining why he believed the Dutch importunities should be answered favourably. He accepted his elevation on 25 January, having not yet received any communications from England due to constant adverse winds.
The Earl had now "the rule and government general" with a Council of State to support him (the members of which he nominated himself). He remained a subject of Elizabeth, making it possible to contend that she was now sovereign over the Netherlands. According to Leicester, this was what the Dutch desired. From the start such a position for him had been implied in the Dutch propositions to the English, and in their instructions to Leicester; and it was consistent with the Dutch understanding of the Treaty of Nonsuch. The English queen, however, in her instructions to Leicester, had expressly declined to accept offers of sovereignty from the United Provinces while still demanding of the States to follow the "advice" of her lieutenant-general in matters of government. Her ministers on both sides of the Channel hoped she would accept the situation as a fait accompli and could even be persuaded to add the rebellious provinces to her possessions. Instead her fury knew no bounds and Elizabeth sent Sir Thomas Heneage to read out her letters of disapproval before the States General, Leicester having to stand nearby. Elizabeth's "commandment" was that the Governor-General immediately resign his post in a formal ceremony in the same place where he had taken it. After much pleading with her and protestations by the Dutch, it was postulated that the governor-generalship had been bestowed not by any sovereign, but by the States General and thereby by the people. The damage was done, however: "My credit hath been cracked ever since her Majesty sent Sir Thomas Heneage hither", Leicester recapitulated in October 1586.
Elizabeth demanded of her Lieutenant-General to refrain at all cost from any decisive action with Parma, which was the opposite of what Leicester wished and what the Dutch expected of him. After some initial successes, the unexpected surrender of the strategically important town of Grave was a serious blow to English morale. Leicester's fury turned on the town's governor, Baron Hemart, whom he had executed despite all pleadings. The Dutch nobility were astonished: even the Prince of Orange would not have dared such an outrage, Leicester was warned; but, he wrote, he would not be intimidate
Robert Dudley, 1st Earl of Leicester