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 succeeded in overcoming resistance and moving 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, in order to attack Lima. Chilean commanders commissioned 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". Neutral military observers closely studied landing tactics and operations during the War of the Pacific: two Royal Navy ships monitored the Battle of Pisagua; United States Navy observer Lt. Theodorus B. M. Mason included an account in his report The War on the Pacific Coast of South America. The with Alfred Thayer Mahan in command, was stationed at Callao, Peru, protecting American interests during the final stages of the War of the Pacific. He formulated his concept of sea power while reading a history book in an English gentleman's club in Lima, Peru. This concept became the foundation for his celebrated The Influence of Sea Power upon History (1890). An amphibious assault took place on the beaches of Veracruz, Mexico in 1914, when the United States Navy attacked and occupied the city as result of the Tampico Affair. Modern operations World War I marked the beginning of the first modern amphibious warfare operations. However, tactics and equipment were still rudimentary and required much improvisation. At the time, British Royal Marine Light Infantry (merged with the Royal Marine Artillery in the 1920s to form the Royal Marines) were used primarily as naval parties onboard Royal Navy warships to maintain discipline and man ships' guns. The RMLI joined a new Royal Navy division, the Royal Naval Division, formed in 1914 (out of those not needed on ships) to fight on land; however, throughout the conflict, army units were depended upon to provide the bulk, if not all, of troops used in amphibious landings. The first amphibious assault of the war was the Battle of Bita Paka (11 September 1914) was fought south