The easier of two commonly used routes on a peak once considered "unscalable from any angle," now known as a straightforward rock scramble once the approach is done.
Access is via the Chiwawa River area northeast of Lake Wenatchee (via Highway 207, the Chiwawa Loop Road, and the Chiwawa River Road/Trail system) using the Buck Creek approach, which shares a parking area with the alternate Chiwawa River Basin approach used by parties combining Fortress with nearby Chiwawa Mountain. From the Buck Creek drainage, climb toward Fortress Mountain's southeast side below the Chiwawa River Basin; a large snowfield sits at the base of the north face and should be avoided in favor of the south and west sides, which are more open and less technical.
Descend the Buck Creek approach route; steep snow lingering into early season calls for an ice axe on both the ascent and descent.