The study of castles by historians and archaeologists developed considerably during the 20th century. The early-20th-century historian and archaeologist Ella Armitage published a ground-breaking book in 1912, arguing convincingly that British castles were in fact a Norman introduction, while historian Alexander Thompson also published in the same year, charting the course of the military development of English castles through the Middle Ages. The Victoria County History of England began to document the country's castles on an unprecedented scale, providing an additional resource for historical analysis.