Why do you think harrriet tubman has the greatest impact on American history? Just need two sentences

Harriet Tubman is perhaps the most well-known of all the Underground Railroad's "conductors." During a ten-year span she made 19 trips into the South and escorted over 300 slaves to freedom. And, as she once proudly pointed out to Frederick Douglass, in all of her journeys she "never lost a single passenger."

Explanation: if need more i can add

the social historical theory explains the creation of the varnas, jats and of the untouchables. according to this theory, the caste system began with the arrival of the aryans in india. the aryans arrived in india around 1500 bc. the fair skinned aryans arrived in india from south europe and north asia.

on the morning of  july 21,  1861, general mcdowell ordered the  unionarmy to attack. it was on this hill that  confederate  colonel thomas jackson and his forces held back theunion  troops.