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Strategy

Control of the sea was Chile's key to an inevitably difficult desert war: supply by sea, including water, food, ammunition, horses, fodder, and reinforcements, was quicker and easier than marching supplies through the desert or across the Bolivian high plateau. While the Chilean Navy started an economic and military blockade of the Allies' ports, Peru took the initiative and used its smaller navy as a raiding force. The raids delayed the ground invasion for six months and forced Chile to shift its fleet from blockading to hunting and capturing the Huáscar. After achieving naval supremacy, sea-mobile forces proved to be an advantage for desert warfare on the long coastline. Peruvian and Bolivian defenders found themselves hundreds of kilometers from home, but the Chilean forces were usually just a few kilometers from the sea.

The Chileans employed an early form of amphibious warfare, which saw the co-ordination of army, navy, and specialized units. The first amphibious assault of the war took place when 2,100 Chilean troops took Pisagua on November 2, 1879. Chilean Navy ships bombarded beach defenses for several hours at dawn, followed by open, oared boats landing army infantry and sapper units into waist-deep water under enemy fire. An outnumbered first landing wave fought at the beach; the second and third waves in the following hours were able to overcome resistance and move inland. By the end of the day, an expeditionary army of 10,000 had disembarked at the captured port. In 1881 Chilean ships transported approximately 30,000 men, along with their mounts and equipment, 500 miles (800 km) in order to attack Lima. Chilean commanders were using purpose-built, flat-bottomed landing craft that would deliver troops in shallow water closer to the beach, possibly the first purpose-built amphibious landing craft in history: "These 36 shallow draft, flat-bottomed boats would be able to land three thousand men and twelve guns in a single wave."

Chile's military strategy emphasized preemption, offensive action, and combined arms. It was the first to mobilize and deploy its forces and took the war immediately to Bolivian and Peruvian territories. It adopted combined arms strategy that used naval and ground forces to rout its allied foes and capture enemy territory. It landed ground forces in enemy territory to raid in strength to split and to drive out defenders, and it then garrisoned the territory as the fighting moved north. Chileans received the support of Chinese immigrants who had been enslaved by Peruvians and joined the Chilean Army during the campaign of Lima and in the raids to the north Peruvian cities.

Peru and Bolivia fought a defensive war, maneuvering through long overland distances and relied when possible on land or coastal fortifications with gun batteries and minefields. Coastal railways reached to central Peru, and telegraph lines provided a direct line to the government in Lima.

The occupation of Peru from 1881 and 1884 took a different form. The theater was the Peruvian Sierra, where the remains of the Peruvian Army had easy access to the population, resource, and supply centers far from the sea, which supported indefinite attrition warfare. The occupying Chilean force was split into small garrisons across the theater and could devote only part of its strength to hunting down dispersed pockets of resistance and the last Peruvian forces in the Sierra. After a costly occupation and prolonged counterinsurgency campaign, Chile sought a diplomatic exit. Rifts within Peruvian society and Peruvian defeat in the Battle of Huamachuco resulted in the peace treaty that ended the occupation.