However, the adherence to the Napoleonic principles in the face of technological advances such as the long-range infantry breechloader rifles and minie ball guns generally led to disastrous consequences for both the Union and Confederate forces and populace. The time and space in which war was waged changed as well. Railroads enabled swift movement of large forces but the manoeuvring was constrained to narrow, vulnerable corridors. Steam power and ironclads changed transport and combat at sea. Newly invented telegraph enabled more rapid communication between armies and their headquarters capitals. Combat was still usually waged by opposing divisions with skirmish lines on rural battlefields, violent naval engagements by cannon-armed sailing or steam-powered vessels, and assault on military forces defending a town.