Sentry Insurance said it is buying nonstandard auto insurer The General from American Family Insurance for about $1.7 billion to mark the largest acquisition in the company’s 120-year history.

Sentry will pay $1.1 billion in cash and assume liabilities and required capital to up the total transaction to $1.7 billion. American Family acquired The General in 2012 when it bought PGC Holdings Corp. and its subsidiaries for $239 million.

Mutual insurer Sentry of Stevens Point, Wisconsin said it is known for business insurance but also has a nonstandard auto, motorcycle, and off-road vehicle insurer in its Dairyland brand, serving customers through its independent-agent network. The purchase of Nashville-based, direct-to-consumer (DTC) The General “brings together two of the strongest brands in the nonstandard auto industry,” said Pete McPartland, chairman and CEO of Sentry.

Sentry said the brands will operate independently during the integration process. The 1,300 or so employees from The General will join Sentry’s workforce of 5,000 on January 1, and will continue to be based in Nashville.

“We’ve found a strategic and cultural fit in Sentry, where the growth and momentum that The General has will continue,” said American Family Insurance CEO Bill Westrate. “We’re confident that Sentry’s expertise, strong reputation in this market and employment culture will not only continue to serve The General’s customers well but will also ease the transition for The General’s employees.”

The transaction is expected to close by the end of the year, pending regulatory approvals.

Late in August, American Family Insurance Group’s Main Street America Insurance said it will stop offering personal lines insurance in favor of a commercial lines strategy.