Overshadowed by the Civil War raging in the East, the hangings in Mankato, Minnesota, on Dec. 26, 1862, followed the often overlooked six-week US-Dakota war earlier that year a war that marked the start of three decades of fighting between Native Americans and the US government across the Plains.

President Abraham Lincoln intervened in the case, demanding a review that reduced the number of death sentences.

But he allowed 38 to be executed, including two men historians believe were hanged in error, even as he was preparing the Emancipation Proclamation to free black slaves in the South.

This month, in an annual event that started in 2005, some Dakota are making a 300-mile trek on horseback in frigid winter temperatures to revive the memory of this footnote in US history.

"It was just a terrible trauma that they had to endure, and we continue to have to endure this generational trauma to this very day," said Sheldon Wolfchild, former chairman of the Lower Sioux Indian Community in southwestern Minnesota.

This year's ride began on Dec. 10 in Crow Creek, South Dakota, the reservation the Dakota were exiled to from Minnesota after the executions. It ends on Dec. 26 in Mankato, where riders will attend a ceremony to remember the hangings.

Center>Copyright Reuters, 2012