"One of the best known catechisms of all time is the Heidelberg Catechism. It is named for a German city, where it was prepared by theologians of the University of Heidelberg at the request of Elector Frederick III, a friend of the Protestant Reformation. Frederick hoped the new catechism would secure harmony among Protestants in his territories and strengthen the hold of the Reformed faith on his provinces. He wrote the preface of the Catechism himself, which is dated this day, January 19, 1563. The Heidelberg Catechism is used by the Reformed Church. Hundreds of thousands of people have memorized it and lived by its teachings over the years since then."
Of course, his plan to unite Protestants didn't go well--today there are about 35,000 different denominations and non-denominations or "just the Bible" churches, which if it weren't for the pro-life movement probably would have little to agree on.