What was it called when both sides fought from behind long ditches they dug with the earth piled in front to protect them?

the monroe doctrine is the best known u.s. policy toward the western hemisphere. buried in a routine annual message delivered to congress by president james monroe in december 1823, the doctrine warns european nations that the united states would not tolerate further colonization or puppet monarchs.

immigrants from northern and western europe continued coming as they had for three centuries, but in decreasing numbers