Shown in the Topo Map to the right, you will see the red line that represents the Cottonwood Lakes / Army Pass Trail. The first 6 1/2 miles of trail is well maintained, while the last 4 miles is an unmaintained but well worn foot path. The last 300 vertical feet must be gained by scrambling up class two rock to the summit.
As noted in the contour lines, the trail starts out gentle, then switchbacks up after a few miles into the cottonwood lakes basin. From there the trail levels out again as it passes through the beautiful meadows and Cottonwood Lakes.
Once past Lake 5, as labeled in the map (but posts a sign labeled Lake 4 on the actual trail), things begin to turn steep. This is part of the unmaintained trail that leads to Old Army Pass. Lots of switchbacks are encountered as it climbs what seems to be a cliff when viewed from below.
I found this section of trail perfectly do-able, and even a little bit exciting. Once you climb out of the basin the trail gives you a super vantage point and you will be treated to some wonderful scenic views of the lakes and meadows below.
The Mt Langley/Cottonwood Lakes Topo Map used with permission from National Geographic http://www.nationalgeographic.com/maps