In 1672, the future of the Republic hung by a thread. It had only happened once during the long years of war with Spain, but the threat was suddenly there again: Holland, the heart of the State, was in danger of being overrun. The menace was warded off, but more through luck than anything else.
A few years after the Treaty of Münster had been signed, the Stadholder no longer had a role to play in the Republic. The citizens had taken control in 1650 and Holland was able to put its own interests above those of the other provinces. People claimed that ‘true liberty' had finally dawned and spoke of a situation in which the ideals of the rebels could, at last, be fully realized.

After 1648, other countries became enemies of the Netherlands. France and England, in particular, looked with envy upon the power that the Republic had obtained thanks to its flourishing trade. In response, the Republic referred to the principle Hugo Grotius had worked out as early as 1609: the sea is free, open to everybody, nobody's property. However, many other countries did not share this standpoint. England, for one, had already taken measures to protect its trade in 1651, thereby triggering a war. In 1664, France followed suit. Led by Johan de Witt, raadpensionaris (councilor pensionary) of Holland and the most powerful statesman in the Republic, the country tried to defend itself with the help of a strong navy and well thought-out diplomacy. Thanks to the victories he gained over England, Admiral Michiel de Ruyter became the country's national hero. Johan de Witt endeavored to play France off against England by diplomatic means. The Republic did not hesitate to take action whenever its commercial interests and the freedom of the seas were at stake, as Sweden experienced in 1658. War, however, was only waged when actual commercial interests were threatened. Otherwise, the Republic's main objective was to maintain a balance of power in Europe.

For a long time, things went well for the Republic and the country became ever richer and more prosperous. In 1672, however, everything went wrong and it looked as if the mighty Republic would collapse like a soufflé. The country's mood was expressed as being ‘redeloos, radeloos, reddeloos' (irrational, distraught, beyond hope); since then the year 1672 has been known as the Year of Disaster. In April, France and England, as well as the bishops of Münster and Cologne, both of whom ruled over a vast territory in Germany, declared war on the Republic. Led by King Louis XIV, the French army marched into the country near Lobith on the river Rhine on 12 June 1672. Since the attack came from an unexpected direction, the east, where the garrisons as well as the fortifications had been neglected for many years in favor of the navy, the Dutch defenses collapsed in no time. The city of Utrecht fell into the hands of the French on 21 June. The allied German troops marched north and soon laid siege to Groningen. Naval engagements also started in June. Admiral De Ruyter had defeated the joint fleet of the French and the English on 7 June, a glimmer of light in the darkness.

In order to defend the key province of Holland, it was decided to use the tried and tested means of inundating the farmlands. A line of defense, the Hollandse Waterlinie, was created, a chain of strongholds and fortified cities surrounded by flooded land. But even this line did not inspire much confidence: everybody was panic-stricken. The government was in despair. Chaos reigned and the authorities threatened to lose control. In many places, people clamored for the return of Orange, the 22 year-old son of William II, the last Stadholder, who had died in 1650: he would have to save the country! Johan de Witt's government had endeavored to get rid of the Orange dynasty, but as early as the beginning of 1672, it was forced to appoint the young William III as commander-in-chief of the army. On 2 July, the States of Zeeland designated him as their Stadholder. All the other provinces soon followed suit. The populous then directed its anger toward Johan de Witt personally. On 20 August, a mob of furious citizens of The Hague lynched him and his brother Cornelis de Witt. This gruesome event illustrates the turmoil the country had fallen into.

The tide turned under William III. One of the reasons was that King Louis XIV had overplayed his hand. He was so sure that victory was already his that he imposed extremely heavy terms for the surrender of the Republic. The Prince of Orange proved furthermore to be a good strategist. He launched a counterattack that same year, relieving Groningen and retaking Maastricht: the Republic had regained the initiative. In 1674, it concluded peace with England, Münster and Cologne and, in 1678, also with France.

The country had stood its ground, but it now knew where the limits to its power lay and the dangers it faced. It had been a most narrow escape. Many of the factors that had played a part in the conflict between Prince Maurice and Johan van Oldenbarnevelt continued to weigh heavily: Holland's inclination to put its own interests above the common interest and its desire for a proper republic, without a monarch. However, although the Orange party now had the upper hand, the Republic's structure was not fundamentally adapted, no more than it had been after 1619. The reinstated Stadholder remained in the service of the States General and had no power of his own. The Republic remained a federation of highly independent provinces and did not become a truly united state.