SEQUOIA NATIONAL PARK, Calif. — On the hillside above Evelyn Lake, deep in the southern Sierra Nevada, it was surprisingly easy to tell time: precisely at noon, a loud whoop echoed amid the black-flecked granite and dust, signaling lunch hour for the 17-person crew repairing the trail to the lake.

“How much rock do you think we moved today?” Gregory Snyder asked his work partner, James Morin, over the metallic clang of rakes, shovels, mallets and pickaxes.

“About five tons,” Mr. Morin guessed. Not bad for a morning’s work building wilderness paths with tools little different from the ones the Egyptians used to build the pyramids. Not bad at all.

Fourteen miles from the nearest road and thousands of miles from the areas of conflict and tension where the two men served in the Army, Mr. Snyder (a former air traffic controller in Iraq) and Mr. Morin (a tank corpsman on the Korean Peninsula) and five other former military men are breaking a trail, figuratively and literally. They are part of a pilot program run by the California Conservation Corps, which gives veterans a chance to learn skills and perhaps pursue careers preserving public lands.