During the american civil war, the 54th massachusetts regiment is most noteworthy for a) defeating the union troops at ft. sumter. b) defending "little round top" at gettysburg. c) being massacred by the confederates at ft. pillow. d) being the first all-black regiment in the u.s. army.

Being the fist all- black regiment in the U,S Army ( D )

Explanation:

The 54th Massachusetts regiment was the first all black regiment in the U.S army during the American civil war. This regiment was a volunteer force and they impressed the Union Army with their heroics as seen with their ill-fated attack at Fort Wagner in south Carolina.

Due to this attack and also been the first all black regiment they became famous and this earned black men the opportunity to be enlisted in the U.S army in the future. they fought gallantly against the confederate forces of the south alongside the union troops. they were led by a white officer named Robert Gould Shaw.