Three of the chairs with wide back and side slats are definitely Brandt Ranch Oak chairs. One still has its original label attached under the seat. The other two oak captain chairs with rounded back slats may be Brandt chairs but are not labeled as such. These chairs came from a dude ranch that operated in the primitive area of Idaho in the mid 1950s.
A Brandt Company was established in 1900 by German immigrant August Brandt. The heavy oak furniture was used in ranch homes, mountain homes, dude ranches, and basement rec rooms across the nation. The US government contracted Ranch Oak furnishings for many of their military bases and it was used by National Park lodges plus roadside motels for its attractive, durable, rustic type of décor. The chairs sell individually for $300 to $500 online.