What does Martin carry with him into the battle at Cowpens? Why is it so special?

A patched up American Flag that his son had carried throughout the war until he died.

Explanation:

His son had died the day before, and while Benjamin mourns him and doubts about his commitment to the war, he founds the flag in his son´s saddlebags. When he shows up to the Battle of Cowpens, horseback with the flag up, Martin shows he has ultimately embraced his convictions and decided to use the flag to give impulse to the exhausted colonial army.

a historian researching the immigration policies of the early 1900s would expect a source written today,rather than in 1910 to :

( a ) be more interested in objective data and statistics.

wisdom

explanation:

the fact that that the teachings on the cosmic order comes from, or through, the heart center