ive ▁against ▁the ▁arm or ▁of ▁the ▁gun bo ats . ▁The ▁primary ▁weapon ▁of ▁each ▁was ▁its ▁rein for ced ▁pro w , ▁ ▁which ▁was ▁intended ▁to ▁be ▁used ▁in ▁ram ming ▁oppon ents . ▁ ▁The ▁Confeder ate ▁r ams ▁were ▁distinguished ▁by ▁a ▁unique ▁feature ▁of ▁their ▁defense ▁against ▁enemy ▁shot . ▁Their ▁engines ▁and ▁other ▁interior ▁spaces ▁were ▁protected ▁by ▁a ▁double ▁bulk head ▁of ▁heavy ▁tim bers , ▁covered ▁on ▁the ▁outer ▁surface ▁by ▁a ▁layer ▁of ▁rail road ▁iron . ▁The ▁gap ▁between ▁the ▁bulk head s , ▁a ▁space ▁of ▁, ▁was ▁pack ed ▁with ▁cot ton . ▁Although ▁the ▁cot ton ▁was ▁the ▁least ▁important ▁part ▁of ▁the ▁arm or , ▁it ▁caught ▁the ▁public ' s ▁attention , ▁and ▁the ▁boats ▁came ▁to ▁be ▁called ▁" cot ton cl ads ". ▁Later ▁in ▁the ▁war , ▁ships ' ▁cre ws ▁were ▁often ▁protected ▁from ▁small - ar ms ▁fire ▁by ▁b ales ▁of ▁cot ton ▁placed ▁in ▁exposed ▁positions , ▁and ▁these ▁vessels ▁were ▁also ▁referred ▁to ▁as ▁" cot ton cl ads ". ▁They ▁differ ed , ▁however , ▁from ▁the ▁original s ▁of ▁the ▁category . ▁ ▁The ▁federal ▁force ▁consisted ▁of ▁five ▁gun bo ats , ▁four ▁of ▁which ▁were ▁known ▁semi - o fficial ly ▁as ▁" E ads ▁gun bo ats ", ▁after ▁their ▁builder , ▁James ▁Buch an an ▁E ads , ▁but ▁more ▁commonly ▁as ▁" P ook ▁t urt les ", ▁after ▁their ▁designer ,