<P> In the end, the war ended through a combination of attrition (of men and material), advances on the battlefield, arrival of American troops in large numbers, and a breakdown of morale and productivity on the German home - front due to an effective naval blockade of her seaports . </P> <P> Aviation in World War I started with primitive aircraft, primitively used . Technological progress was swift, leading to ground attack, tactical bombing, and highly publicized, deadly dogfights among aircraft equipped with forward - firing, synchronized machine guns from July 1915 onwards . However, these uses made a lesser impact on the war than more mundane roles in intelligence, sea patrol and especially artillery spotting . Antiaircraft warfare also had its beginnings in this war . </P> <P> As with most technologies, aircraft and their use underwent many improvements during World War I. As the initial war of movement on the Western Front settled into trench warfare, aerial reconnaissance over the front added to the difficulty of mounting surprise attacks against entrenched and concealed defenders . </P> <P> Manned observation balloons floating high above the trenches were used as stationary observation posts, reporting enemy troop positions and directing artillery fire . Balloons commonly had a crew of two, each equipped with parachutes: upon an enemy air attack on the flammable balloon, the crew would jump to safety . At the time, parachutes were too heavy to be used by pilots in aircraft, and smaller versions would not be developed until the end of the war . (In the British case, there arose concerns that they might undermine morale, effectively encouraging cowardice .) Recognized for their value as observer platforms, observation balloons were important targets of enemy aircraft . To defend against air attack, they were heavily protected by large concentrations of antiaircraft guns and patrolled by friendly aircraft . </P>

How did changes in technology make wwi different than wwi