They, in conclusion, very politely informed King Henry IV. himself, that if he wished to unite with them, he must sign their creed.  This was sincerity, honesty, but it was the sincerity and honesty of minds but partially disinthralled from the bigotry of the dark ages.  While the Protestants were thus unhappily disunited, the pope cooeperated with the emperor, and wheeled all his mighty forces into the line to recover the ground which the papal church had lost.  Several of the more enlightened of the Protestant princes, seeing all their efforts paralyzed by disunion, endeavored to heal the schism.  But the Lutheran leaders would not listen to the Calvinists, nor the Calvinists to the Lutherans, and the masses, as usual, blindly followed their leaders.

Several of the Calvinist princes and nobles, the Lutherans refusing to meet with them, united in a confederacy at Heilbrun, and drew up a long list of grievances, declaring that, until they were redressed, they should withhold the succors which the emperor had solicited to repel the Turks.  Most of these grievances were very serious, sufficiently so to rouse men to almost any desperation of resistance.  But it would be amusing, were it not humiliating, to find among them the complaint that the pope had changed the calendar from the Julian to the Gregorian.

By the Julian calendar, or Old Style as it was called, the solar year was estimated at three hundred and sixty-five days and six hours; but it exceeds this by about eleven minutes.  As no allowance was made for these minutes, which amount to a day in about one hundred and thirty years, the current year had, in process of ages, advanced ten days beyond the real time.  Thus the vernal equinox, which really took place on the 10th of March, was assigned in the calendar to the 21st.  To rectify this important error the New Style, or Gregorian calendar, was introduced, so called from Pope Gregory XII.  Ten days were dropped after the 4th of October, 1582, and the 5th was called the 15th.  This reform of the calendar, correct and necessary as it was, was for a long time adopted only by the Catholic princes, so hostile were the Protestants to any thing whatever which originated from the pope.  In their list of grievances they mentioned this most salutary reform as one, stating that the pope and the Jesuits presumed even to change the order of times and years.

This confederacy of the Calvinists, unaided by the Lutherans, accomplished nothing; but still, as year after year the disaffection increased, their numbers gradually increased also, until, on the 12th of February, 1603, at Heidelberg they entered into quite a formidable alliance, offensive and defensive.