During the U.S.-Dakota War, Col. Henry Sibley and Dakota Chief Little Crow left notes for each other in notches of trees. How things have changed in 150 years.

You can now use your cellphone to augment your visits to historic sites from the 1862 war. Here's how it works:

Call 1-888-601-3010 from anywhere -- your mobile phone, home phone, the road.

From there, follow the menu to hear everything from Dakota poetry to settlers' perspectives. Each comes in 30- to 45-second audio chunks and offers you other options to dig deeper. Touching the * key at any time gets you back to the main menu. It's that simple.

A two-digit code lets you hear an introduction with Dakota origin stories (#01), plus more about these sites:

Traverse de Sioux (#02), the site of a key 1851 treaty signing near St. Peter that saw the Dakota handing over their traditional lands for a ribbon of reservation land along the Minnesota River, in exchange for often unfulfilled pledges for money, food and goods.

New Ulm (#03), the town that became the epicenter of battles in the war's first week.

Lower Sioux Agency (#04), the small village of stores and warehouses that became the first scene of violence on Aug. 18, 1862. The warehouse still stands that held food that was denied to the starving Dakota.

Birch Coulee Battlefield (#05), the prairie scene of a 36-hour siege during which the Dakota surprised a burial party.

Upper Sioux Agency (#06), farther up the Minnesota River near Granite Falls, the other government-built center of operations created when the reservations were set up after the 1851 treaty.

Camp Release (#07), the site near Granite Falls where the hostages were released at the end of the war.

CURT BROWN