In 1660, when his uncle was restored as King of England, his mother went there only to die of smallpox. He now became more important politically and in 1666 was declared a "Child of State" with the States of Holland taking over the responsibility for his education. In 1668 he was declared the First Noble of Zeeland and from his eighteenth birthday onward managed his own estates. In the meantime the French became menacing to The Netherlands as they attacked the Spanish Netherlands (now Belgium). In 1670 Louis XIV and Charles II made a secret treaty in which they intended to divide The Netherlands between them. Also in 1670 William was invited to England and stayed for four months. In 1671 and 1672 Louis XIV's intentions became more obvious with popular supporters wanting William to be made Captain-General, though this was at first rejected by the States' party. However, his appointment was soon made, only to be followed by Louis XIV's attack. In May 1672 the French proceeded so far into The Netherlands that Johan de Witt, in charge of the Dutch government, ordered the dikes to be broken in order to create a line of defence and so protect the province of Holland.

Fortunately, Louis XIV hesitated, thus giving the Dutch time both to strengthen their defence and increase their army. They then felt in a position to reject Louis XIV's unacceptable demands. On 24 June 1672 William was at last made 'stadhouder' and, consequently, was in charge of The Netherlands. Continuing riots caused Johan de Witt to resign as Grand Pensionary and, when a letter of Charles II became known in which he blamed the States for the war, the rabble in The Hague murdered Johan de Witt and his brother Cornelis.
With these murders removing the last barriers, William now took effective power in The Netherlands. From now on for the rest of his life his policy was the containment of France. Over the following years William had to fight many battles, losing a good deal of them.
In 1674 he had to fight the Great Cond‚ at Seneffe who maintained: "The Prince of Orange has acted in all respects like an old captain, except in venturing his life too much like a young one." As a diplomat he had hoped for the support of his uncle, Charles  II. However, when he realized Charles II's intentions, he was forced to give secret support to the opposition in England. His position there became stronger when his other uncle, the Duke of York, became a Catholic and, to counteract this, William was allowed to marry Mary,
the Protestant eldest daughter of the Duke of York. Although William held contempt for the low birth of Mary's mother, Ann Hyde, he hoped it would strengthen his position with Charles II. Not only were his original motives diplomatic but Mary at first found him unattractive. He was almost twenty-seven and she fifteen. The marriage was popular in England and after a dreadful crossing they settled in Holland. Early in 1678 she became pregnant but miscarried. Once more she thought she was pregnant but, after nine months, it became obvious that no child was coming. Yet their marriage improved personal conduct. As well, Mary had also become popular in Holland.

Meanwhile relations with Charles II had worsened; but when Charles II died on 6 February 1685, William's father-in-law became King James II. In England James II was accepted and, as his second marriage had not produced any surviving children, it was expected that in due course he would be succeeded by his daughter, Mary. Relations with the new king were difficult as James II resented English republicans finding refuge in Amsterdam. At this time Mary discovered that William was having an affaire with Elizabeth Villiers, one of her
maids-of-honour, and for a short while their relationship cooled. In August 1687 William sent his cousin, Zuylestein, to England where he built up an intelligence network. Late in 1687 it was announced that James II's wife was pregnant and, when a son was born on 10 June 1688, English nobles asked William to act. They feared that James II would bring his son up as a Catholic and then force Catholicism on England. After he was assured that the French king would not attack The Netherlands, he prepared for an invasion of England. On 1 November 1688 the invasion began and, on 5 November, he landed near Brixham. Soon he was joined by the English while James II left London to join his army near Salisbury. However, James II was now a broken man deserted by many: amongst them his nephew, Lord Cornbury, and then his other daughter, Anne. He then left for France where his wife and son were already waiting.

At first it was suggested that William III would become sole king; however, the English objected as Mary was regarded as the rightful heir. Mary then objected to becoming Queen alone, with the result that the Crown was offered to them jointly. Mary then had to leave Holland and reluctantly return to England. William III surrounded himself with Dutchmen and only a few Englishmen. The Dutch regarded England as "a devilish country, so dirty and wicked". Not only was William homesick but Mary, too, was unhappy. Mary then headed a regency council while William, with a large army, went to Ireland where James II, also with an army, had landed. At the Boyne a decisive battle was fought with James II returning to exile in France.
William III and Mary II now settled in as King and Queen, although both, being shy, disliked the pomp that came with it. As well, even though William was now able to hold the alliance to contain France, the English still did not like him. Whenever William was campaigning
abroad, Mary presided over the regency council ruling England. Although she had no experience and not been brought up to rule, she performed her task admirably. She and William were now closer than ever and she not only missed him whenever he was abroad but longed to return to Holland. Another reason for Mary's unhappiness was the deteriorating relationship with her sister, Princess Anne, mainly caused by Sarah Churchill, Countess of Marlborough. The break came in 1691 and, in January 1692, the Earl of Marlborough was dismissed from all his offices. A few days later, when Princess Anne arrived at Court with the Countess of Marlborough, Mary was infuriated. When she ordered her sister to dismiss Sarah, Anne refused. Consequently the two sisters never spoke to each other again.
On 28 December 1694 Mary II died of smallpox and, when the distraught William III collapsed at her bedside, Hans Willem Bentinck, Earl of Portland, had to carry him to bed. It took a month before William began to recover but for a long time afterwards he was still
subject to sudden fits of weeping. Later he became reconciled with Princess Anne, both according her a place of honour as heir apparent and using her as his hostess whenever required. By 1695 it became obvious that Portland's position as William III's favourite had been replaced by Keppel, another Dutchman, and, in most of his time abroad and in 1699 resigned his offices. However, during these years the continental wars continued, playing havoc with England's finances. It took the treaty of Rijswijk in 1697 to make peace at last but by which Louis XIV had to abandon most of what he had taken since 1678.
With the end of the war in England, there was no longer the need for unity and soon there were arguments about both taxation and a vindictive Parliament. However, from now on the main European problem was the Spanish succession, with the situation complex and delicate.
Apart from having to wait for the demise of King Carlos II on 1 November 1700 for Louis XIV to accept Spain for his grandson, it would take until 1715 before matters could be settled. In the period immediately after the death of Carlos II, the French provoked the Dutch and English even though all three countries were neither prepared for nor wanted war. However, William III had secured a Parliament which would support him vigorously. From 1701 onwards the swelling of his legs grew worse so that at times he was unable to walk. He then began to realise that he would not see the end of this war, let alone lead the army in person. To assure that the war would be carried on as he would want it to, he groomed both Heinsius in Holland and the Earl of Marlborough in England.
On 21 February 1702, with his health just beginning to improve, he was riding in Richmond Park when his horse stumbled on a molehill and he fell and broke his collar-bone. Now unable to take exercise at all, his legs again began to swell. By 7 March he had fever and became very ill. Although in great pain, he nevertheless remained clear of mind, knowing his death to be near. He died on 8 March 1702.
William III was one of the great men of his time with his main achievement the containment of France; yet, as remarked by Bishop Gilbert Burnet, "In death as in life, the English would not accord William the respect he deserved".
 

Source: Leo van de Pas