Supercell have announced that the summer Clash of Clans update will feature a tweak to the API. Their aim is to make war history available for the last 50 wars.
Supercell are conflicted by releasing this data as they wish to respect the privacy of every clan. They have resolved the issue by allowing the clan leader or possibly co-leader to make this data publicly available.
If clans’ War log is public, it can be queried with a new API call. This will be a new setting in-game, most likely set to “on” by default but Clans can choose to make the results private at any given time.
Having this API data available will allow Clash of Stats and other similar websites to maintain these records past 50 wars.