Complex sentence: Though nominally the servant of the States of Holland he made himself politically the personification of the province which bore more than half the entire charge of the union, and as its mouthpiece in the States-General he practically dominated that assembly.
Split into simpler sentences: Though nominally the servant of the States of Holland, he made himself the political personification of the province which bore more than half the entire charge of the union. As its mouthpiece in the States-General, he practically dominated that assembly.