The Habsburg monarchy was thus a union of crowns, with no single constitution or shared institutions other than the Habsburg court itself, with territories inside and outside the Holy Roman Empire that were united only in the person of the monarch. The composite state became the most common dominant form of monarchies in the European continent during the early modern era. The unification of the Habsburg monarchy took place in the early 19th century. The Habsburg Monarchy was formally unified from 1804 to 1867 as the Austrian Empire and from 1867 to 1918 as the Austro-Hungarian Empire. It collapsed following defeat in the First World War.