The position of John de Witt in July, 1654, was a difficult one. The conduct of the council-pensionary in the matter of the Act of Exclusion was openly attacked in the States-General. Had the leaders of the Orange party been united, the attack might have had serious consequences; but notoriously the princess royal, the princess dowager and William Frederick were on bad terms, and De Witt, with his usual adroitness, knew well how to play off one against another. To meet the accusations of his assailants in the States-General he drew up however an elaborate defence of the action taken by the Estates of Holland and by himself. The document bore the title "Deduction of the Estates of Holland." It was laborious rather than convincing, and it did not convince opponents. Nevertheless, though resentment continued to smoulder, the fact that peace had been assured soon reconciled the majority to allow the doubtful means by which it had been obtained to be overlooked. The tact, the persuasiveness, the great administrative powers of the council-pensionary effected the rest; and his influence from this time forward continued to grow, until he attained to such a control over every department of government, as not even Oldenbarneveldt had possessed in the height of his power.

John de Witt was possibly not the equal of the famous Advocate in sheer capacity for great affairs, but he had practical abilities of the highest order as a financier and organiser, and he combined with these more solid qualifications a swiftness of courageous decision in moments of emergency which his almost infinite resourcefulness in extricating himself from difficult and perilous situations, enabled him to carry to a successful issue. His marriage in February, 1655, to Wendela Bicker, who belonged to one of the most important among the ruling burgher-families of Amsterdam, brought to him enduring domestic happiness. It was likewise of no slight political value. Andries and Cornelis Bicker, who had headed the opposition to William II and had been declared by him in 1650 incapable of holding henceforth any municipal office, were her uncles; while her maternal uncle, Cornelis de Graeff, was a man of weight and influence both in his native town and in the Provincial Estates. By this close relationship with such leading members of the regent-aristocracy of Amsterdam the council-pensionary became almost as secure of the support of the commercial capital in the north of Holland, as he was already of Dordrecht in the south. Two of his cousins, Slingelandt and Vivien, were in turn his successors, as pensionaries of Dordrecht, while for his predecessor in that post, Nicolas Ruysch, he obtained the extremely influential office ofgriffier or secretary to the States-General. Nor did he scruple to exercise his powers of patronage for other members of his family. His father, Jacob de Witt, was made a member of the Chamber of Finance; his elder brother, Cornelis, Ruwaard of Putten. By these and other appointments of men who were his friends and supporters, to important positions diplomatic, military and naval, De Witt contrived to strengthen more and more his personal authority and influence. And yet in thus favouring his relatives and friends, let us not accuse De Witt of base motives or of venality. He firmly believed in his own ability to serve the State, and, without doubt, he was convinced that it was for the best interest of his country for him to create for himself, as far as was possible amidst the restrictions by which he was hemmed in on every side, a free field of diplomatic and administrative action. No one, not even his bitterest enemies, ever charged John de Witt with personal corruption. Throughout his whole career he lived quietly and unostentatiously, as a simple citizen, on a very moderate income, and he died a poor man.

One of the first cares of the council-pensionary after the peace with England was to deal with the internal troubles which were disturbing certain parts of the land, notably Groningen, Zeeland and Overyssel. In the last-named province a serious party struggle arose out of the appointment of a strong Orangist, named Haersolte, to the post of Drost or governor of Twente. The Estates were split up, the Orange partisans meeting at Zwolle, the anti-Orange at Deventer. Both enlisted troops, but those of Zwolle were the stronger and laid siege to Deventer. The victorious Orangists then nominated William III as stadholder with William Frederick as his lieutenant. At last, after three years' strife, the parties called in De Witt and William Frederick as mediators. But De Witt was far too clever for the Friesland stadholder. It happened that the post of field-marshal had just fallen vacant by the death of Brederode. Both William Frederick and his cousin Joan Maurice aspired to the office. The council-pensionary induced his co-mediator, with the hope of becoming Brederode's successor, to yield on all points. Haersolte was deprived of office; the prince's appointment as stadholder was suspended until his majority; and therefore William Frederick could not act as his lieutenant. Thus peace was restored to Overyssel, but William Frederick was not appointed field-marshal. In the other provinces the tact and skill of De Witt were equally successful in allaying discord. He would not have been so successful had the Orange party not been hopelessly divided and had it possessed capable leaders.