Artillery battery in the context of "Main battery"

Castillo San Cristóbal (English: Saint Christopher Castle) is a fortress in the Old San Juan historic quarter of San Juan, the capital municipality of Puerto Rico, known for being the largest fortification built by the Spanish in the New World. Dating back to defense expansions following attacks by the English in 1598 and Dutch in 1625, it was first constructed in 1634 as the Caballero de San Miguel (Saint Michael Cavalier) and the Garita del Diablo ("devil’s sentry box"). Over the next 150 years, especially in the reign of King Charles III of Spain, it continued to be developed into a bastion fort with outer ravelins and batteries to reach its largest size in 1783. Rising 150 ft from the Atlantic shoreline, the three-level edifice stands on a hill at the northern coastline of San Juan Islet, guarding the land entry to Old San Juan. Alongside El Morro, La Fortaleza, and other forts part of the Walls of Old San Juan, it protected strategically and militarily important Puerto Rico, or La Llave de las Indias (The Key to the Indies), from invasion by competing world powers during the Age of Sail. It was designated a World Heritage Site by UNESCO in 1983.

The Battery, formerly known as Battery Park, is a 25-acre (10 ha) public park located at the southern tip of Manhattan Island in New York City facing New York Harbor. The park is bounded by Battery Place on the north, with Bowling Green to the northeast, State Street on the east, New York Harbor to the south, and the Hudson River to the west. The park contains attractions such as an early 19th-century fort named Castle Clinton; multiple monuments; and the SeaGlass Carousel. The surrounding area, known as South Ferry, contains multiple ferry terminals, including the Staten Island Ferry's Whitehall Terminal; a boat launch to the Statue of Liberty National Monument (which includes Ellis Island and Liberty Island); and a boat launch to Governors Island.

The park and surrounding area are named for the artillery batteries that were built in the late 17th century to protect the fort and settlement behind them. By the 1820s, the Battery had become an entertainment destination and promenade, with the conversion of Castle Clinton into a theater venue. During the mid-19th century, the modern-day Battery Park was laid out and Castle Clinton was converted into an immigration and customs center. The Battery was commonly known as the landing point for immigrants arriving in New York City until 1892, when the immigration center was relocated to Ellis Island in the middle of the harbor. Castle Clinton (sometimes called, Castle Garden) then hosted the New York Aquarium from 1896 to 1941.

The howitzer (/ˈhaʊ.ɪtsər/) is an artillery weapon that falls between a cannon (or field gun) and a mortar. It is capable of both low angle fire like a field gun and high angle fire like a mortar, given the distinction between low and high angle fire breaks at 45 degrees or 800 mils (NATO). With their long-range capabilities, howitzers can be used to great effect in a battery formation with other artillery pieces, such as long-barreled guns, mortars, and rocket artillery. Howitzers were valued for their ability to fire explosive shells and incendiary materials into fortifications.

Throughout the 18th and 19th centuries, howitzers evolved to become more mobile and versatile. The introduction of rifling in the mid-19th century led to significant changes in howitzer design and usage. By the early 20th century, howitzers were classified into different categories based on their size and role, including field howitzers, siege howitzers, super-heavy siege howitzers, and defence howitzers.

A broadside is the side of a ship, or more specifically the battery of cannon on one side of a warship or their coordinated fire in naval warfare, or a measurement of a warship's maximum simultaneous firepower which can be delivered upon a single target (because this concentration is usually obtained by firing a broadside). From the 16th century until the early decades of the steamship, vessels had rows of guns set in each side of the hull. Firing all guns on one side of the ship became known as a "broadside". The cannon of 18th-century men of war were accurate only at short range, and their penetrating power mediocre, which meant that the thick hulls of wooden ships could only be pierced at short ranges. These wooden ships sailed closer and closer towards each other until cannon fire would be effective. Each tried to be the first to fire a broadside, often giving one party a decisive headstart in the battle when it crippled the other ship.

The Atlantic Wall (German: Atlantikwall) was an extensive system of coastal defences and fortifications built by Nazi Germany between 1942 and 1944 along the coast of continental Europe and Scandinavia as a defence against an anticipated Allied invasion of Nazi-occupied Europe from the United Kingdom, during World War II. The manning and operation of the Atlantic Wall was administratively overseen by the German Army, with some support from Luftwaffe ground forces. The Kriegsmarine (German Navy) maintained a separate coastal defence network, organised into a number of sea defence zones.

Hitler ordered the construction of the fortifications in 1942 through his Führer Directive No. 40. More than half a million French workers were drafted to build it. The wall was frequently mentioned in Nazi propaganda, where its size and strength were usually exaggerated. The fortifications included colossal coastal guns, batteries, mortars, and artillery, and thousands of artillery pieces were stationed in its defences. Today, ruins of the wall exist in all of the nations where it was built, although many structures have fallen into the ocean or have been demolished over the years.

Battery cages are a housing system used by factory farms for various animal production methods, but primarily for egg-laying hens. The name arises from the arrangement of rows and columns of identical cages connected, in a unit, as in an artillery battery. Although the term is usually applied to poultry farming, similar cage systems are used for other animals. Battery cages have generated controversy between advocates for animal welfare and industrial producers.

A blockhouse is a small fortification, usually consisting of one or more rooms with loopholes, allowing its defenders to fire in various directions. It is usually an isolated fort in the form of a single building, serving as a defensive strong point against any enemy that does not possess siege equipment or, in modern times, artillery, air force or cruise missiles. A fortification intended to resist these weapons is more likely to qualify as a fortress or a redoubt, or in modern times, be an underground bunker. However, a blockhouse may also refer to a room within a larger fortification, usually a battery or redoubt.

Fort Ward was a Confederate States of America fort located in Wakulla County, Florida, at the confluence of the Wakulla River and St. Marks River and named after Colonel George T. Ward, owner of Southwood Plantation, Waverly Plantation, and Clifford Place Plantation south of Tallahassee. During the American Civil War, Confederate troops placed a battery of cannons at Fort Ward.