The Dutch saw, with the utmost regret, a war approaching, whence they might dread the most fatal consequences, but which afforded no prospect of advantage. They tried every art of negotiation, before they would come to extremities. Their measures were at that time directed by John de Wit, a minister equally eminent for greatness of mind, for capacity, and for integrity. Though moderate in his private deportment, he knew how to adopt in his public counsels that magnanimity, which suits the minister of a great state. It was ever his maxim, that no independent government should yield to another any evident point of reason or equity; and that all such concessions, so far from preventing war, served to no other purpose than to provoke fresh claims and insults. By his management a spirit of union was preserved in all the provinces; great sums were levied; and a navy was equipped, composed of larger ships than the Dutch had ever built before, and able to cope with the fleet of England.--David Hume, History of England.
Johan De Witt is introduced (in 1665) with superlative qualifications as a magnanimous leader by David Hume in his History of England (recall). Hume emphasizes that De Wit is willing to negotiate to prevent war; but De Witt won't yield not on matters of principle ("reason") or justice ("equity"). To avoid confusion, such justice is also a matter of self-interest because by Hume's lights there is little difference between justice/equity and property (see here for a defense of that claim). Among his other qualities praised is his ability to preserve even promote unity in a confederation (the Dutch Republic) that was notoriously incapable of such unity. To generate and maintain unity, guided and constrained by reason and equity, is the political act as such. Hume also intimates that to stand on principle or justice when one is not capable of or unwilling to sacrifice for independence is, while noble, an act of foolishness.
Now, De Witt, who was one of the leading mathematicians of his age and trained in the cutting edge of Cartesian philosophy, is as close to a philosopher-king we have seen in the modern age (comparable to Marcus Aurelius in the Ancient world). Hume makes the point (with an allusion to Republic 488e–489d) a few lines below: The genius of this man was of the most extensive nature. He quickly became as much master of naval affairs, as if he had from his infancy been educated in them; and he even made improvements in some parts of pilotage and sailing, beyond what men expert in those arts had ever been able to attain. Throughout his treatment of De Witt, Hume reminds the reader of his strength of mind under duress.* Even so, we know that De Witt's rule (and life) will end badly. Hume introduces the fall as follows:
Though de Wit’s intelligence in foreign courts was not equal to the vigilance of his domestic administration, he had, long before, received many surmises of this fatal confederacy; but he prepared not for defence, so early or with such industry, as the danger required. A union of England with France was evidently, he saw, destructive to the interests of the former kingdom; and therefore, overlooking or ignorant of the humours and secret views of Charles, he concluded it impossible, that such pernicious projects could ever really be carried into execution. Secure in this fallacious reasoning, he allowed the republic to remain too long in that defenceless situation, into which many concurring accidents had conspired to throw her.--Hume. [Emphasis added.]
De Witt is treated as an instance of rational over-confidence. De Witt treats his country's potential enemies as rational, calculating agents--ones that understand their own self-interests properly and that will act accordingly (in the context of a balance of power). In the grip of a model of reality, De Witt treats something as impossible that he ought to prepare for. Hume here deviates from Spinoza's analysis (recall) explicitly treats De Witt's power, and subsequent fall, as evidence for the bad institutional design of the Dutch (oligarchic) aristocracy of his age. (Hume is not against such explanations, as his treatment of Genoa very nicely exhibits in his essay, "That Politics May be Reduced to a Science.") But, not unlike Spinoza, Hume recognizes the limits of a political science that treats the world as populated with rational agents acting in their own best interests.
De Witt's failure of scientific imagination is exacerbated by the fact that "by a continued and successful application to commerce, the [Dutch] were become unwarlike, and confided entirely for their defence in that mercenary army, which they maintained." Here Hume echoes Machiavelli's injunction against reliance on mercenaries. And taken out of context, one might also assume that Hume agrees with those Republican authors of his day that declaimed against the vices of luxury and commerce (for Hume's considered views, see "Of Commerce."and "Of Refinement in the Arts.")
But the deeper problem that Hume diagnoses, and this brings him unexpectedly close to, and deepens, Spinoza's analysis, is that the Dutch were not a true unity and so, because of lack of mutual trust had fired the experienced officer corps of the Dutch army thought too loyal to the Orangist faction (and so were unprepared to do real battle). In addition, while De Witt had been careful to prevent corruption in naval manners, he had allowed a form of oligarchic crony-ism seep into the military affairs: "these new officers, relying on the credit of their friends and family, neglected their military duty; and some of them, it is said, were even allowed to serve by deputies, to whom they assigned a small part of their pay."**
*Hume also points out, and approves, of De Witt's willingness to break Dutch law in order to pass rapidly a treaty (The Triple League) deemed necessary for public interests.
** One is reminded of the present Iraqi army.