The conclusion of the truce did not bring, with material progress and trade expansion, internal peace to the United Provinces. The relations between the Prince-stadholder and the all-powerful Advocate had long been strained. In the long-drawn-out negotiations Maurice had never disguised his dislike to the project of a truce, and, though he finally acquiesced, it was a sullen acquiescence. At first there was no overt breach between the two men, but Maurice, though he did not refuse to meet Oldenbarneveldt, was cold and unfriendly. He did not attempt to interfere with the old statesman's control of the machinery of administration or with his diplomatic activities, for he was naturally indolent and took little interest in politics. Had he been ambitious, he might many years before have obtained by general consent sovereign power, but he did not seek it. His passion was the study of military science. From his early youth he had spent his life in camps, and now he found himself without occupation. The enemies of Oldenbarneveldt seized the opportunity to arouse Maurice's suspicions of the Advocate's motives in bringing about the truce, and even to hint that he had been bribed with Spanish gold. Chief among these enemies was Francis van Aerssens, for a number of years ambassador of the States at Paris. Aerssens owed much to the Advocate, but he attributed his removal from his post at the French court to the decision of Oldenbarneveldt to replace him by his son-in-law, Van der Myle. He never forgave his recall, and alike by subtle insinuation and unscrupulous accusation, strove to blacken the character and reputation of his former benefactor.

By a curious fatality it was the outbreak of fierce sectarian strife and dissension between the extreme and the moderate Calvinists which was eventually to change the latent hostility of Maurice to Oldenbarneveldt into open antagonism. Neither of the two men had strong religious convictions, but circumstances brought it about that they were to range themselves irrevocably on opposite sides in a quarrel between fanatical theologians on the subject of predestination and grace.

From early times Calvinism in the northern Netherlands had been divided into two schools. The strict Calvinists or "Reformed," known by their opponents as "Precisians," and the liberal Calvinists, "the Evangelicals," otherwise "the Libertines." To this Libertine party belonged William the Silent, Oldenbarneveldt and the majority of the burgher-regents of Holland. These men regarded the religious question from the statesman's point of view. Having risen in rebellion against the tyranny of the Spanish Inquisition, they were anxious to preserve their countrymen (only a minority of whom were Protestants) from being placed under the heel of a religious intolerance as narrow and bigoted as that from which they had escaped. The "Reformed" congregations on the other hand, led by the preachers, were anxious to summon a National Synod for the purpose of creating a State Church to whose tenets, rigidly defined by the Heidelberg catechism and the Netherland confession, all would be required to conform on pain of being deprived of their rights as citizens. The Libertines were opposed to such a scheme, as an interference with the rights of each province to regulate its own religious affairs, and as an attempt to assert the supremacy of Church over State.