Task: Question Understanding
Input (English): Passage: The county was formed in 1752 from parts of Bladen, Granville, and Johnston Counties. It was named for the infant William V of Orange, whose mother Anne, daughter of King George II of Great Britain, was then regent of the Dutch Republic. In 1771, Orange County was greatly reduced in area. The western part of it was combined with the eastern part of Rowan County to form Guilford County. Another part was combined with parts of Cumberland County and Johnston County to form Wake County. The southern part of what remained became Chatham County. In 1777, the northern half of what was left of Orange County became Caswell County. In 1849, the western third of the still-shrinking county became Alamance County. Finally, in 1881, the eastern half of the county's remaining territory was combined with part of Wake County to form Durham County. Some of the first settlers of the county were English Quakers, who settled along the Haw and Eno Rivers. Arguably, the earliest settlers in the county were the Andrews family, which would later marry into the Lloyd family.
Question: the northern half of what was left of Orange County became Caswell County in?
Output (English): date