1. Why are slave masters along Maryland's Eastern Shore concerned? What do they do in response?

Maryland remained in the Union, but slavery remained a reality in Maryland's agricultural areas like the Eastern Shore.  President Lincoln's Emancipation Proclamation, which went into effect Jan. 1, 1863, technically applied to the states that had seceded.  Maryland did not act to end slavery within its borders until November 1, 1864.

yes, it can be both.