Complex sentence: In 1914 he had accompanied Mihály Károlyi to the United States and since then was one of his closest friends; during the crisis of the end of the war, he led large protests at the Royal Palace of Budapest to demand a government of Károlyi.
Split into simpler sentences: In 1914 he had accompanied Mihály Károlyi to the United States and since then was one of his closest friends. During the crisis of the end of the war, he led large protests at the Royal Palace of Budapest to demand a government of Károlyi.