Question:  Arthur Machen was a Welsh author and mystic of the 1890s and early 20th century well known for his leading role in creating the legend of the Angels of Mons, a popular legend about a group of angels who supposedly protected members of what army?

Context articles: Arthur Machen
Maysville Historic District (Mobile, Alabama)
Rockdale (Fallston, Maryland)
John Gresham Machen
Weird fiction
Melingriffith Brass Band
History of ecology
Šajkača
Arlington's Great Meadows
Angels of Mons

Arthur Machen ( ; 3 March 1863 – 15 December 1947) was a Welsh author and mystic of the 1890s and early 20th century.
 He is best known for his influential supernatural, fantasy, and horror fiction.
 His novella "The Great God Pan" (1890; 1894) has garnered a reputation as a classic of horror (Stephen King has called it "Maybe the best [horror story] in the English language").
 He is also well known for his leading role in creating the legend of the Angels of Mons.
The Maysville Historic District is a historic district in Mobile, Alabama.
 The district covers 451 acre and contains 1121 properties located southwest of downtown and directly south of the Leinkauf Historic District.
 Platted in 1871 in the midst of a recession in Mobile, the neighborhood did not begin to develop until the late 1890s.
 Maysville has long been a working class neighborhood; many late 1890s and early 1900s houses were bungalows and cottages, some with modest Victorian influences.
 Some larger and more decorated houses were built in the northeastern portion of the neighborhood.
 In the early 20th century and into World War I and World War II, the Port of Mobile and its shipyards became a focus of Mobile's economy, and the population grew in response.
 The early 20th century saw many craftsman-style bungalows and four square houses built.
 Minimalist Traditional and some ranch-style houses became popular around and after World War II.
 Notable contributing buildings in the district are Ladd–Peebles Stadium, built in 1948, and Williamson High School, built in 1965.
 The district was listed on the National Register of Historic Places in 2013.
Rockdale, also known as The Robinson/Stirling Place, is a historic home and farm complex located at Fallston, Harford County, Maryland, United States.
 It is a farm developed from the late 18th century through the early 20th century.
 The dwelling is in three parts.
 The east room of the east wing is the earliest section dating from the 18th century.
 The largest or main portion of the dwelling dates from between 1815 and 1830.
 The north wing, a bay centered in the south façade of the second story, and a small conservatory, date from the very early 20th century.
 The main house is five bays in length, two and a half stories, of stone construction, stuccoed and scored.
 The home is surrounded by several outbuildings, trees, and other plantings, and the remains of formal gardens and garden structures developed in the early 20th century.
 It was the residence of William E. Robinson (1860-1935), an entrepreneur in the local canning industry.
John Gresham Machen ( ; July 28, 1881 – January 1, 1937) was an American Presbyterian theologian in the early 20th century.
 He was the Professor of New Testament at Princeton Seminary between 1906 and 1929, and led a conservative revolt against modernist theology at Princeton and formed Westminster Theological Seminary as a more orthodox alternative.
 As the Northern Presbyterian Church continued to reject conservative attempts to enforce faithfulness to the Westminster Confession, Machen led a small group of conservatives out of the church to form the Orthodox Presbyterian Church.
 When the northern Presbyterian church (PCUSA) rejected his arguments during the mid-1920s and decided to reorganize Princeton Seminary to create a liberal school, Machen took the lead in founding Westminster Seminary in Philadelphia (1929) where he taught New Testament until his death.
 His continued opposition during the 1930s to liberalism in his denomination's foreign missions agencies led to the creation of a new organization, the Independent Board for Presbyterian Foreign Missions (1933).
 The trial, conviction and suspension from the ministry of Independent Board members, including Machen, in 1935 and 1936 provided the rationale for the formation in 1936 of the OPC.
Weird fiction is a subgenre of speculative fiction originating in the late 19th and early 20th centuries.
 It can be said to encompass the ghost story and other tales of the macabre.
 Weird fiction is distinguished from horror and fantasy in its blending of supernatural, mythical, and even scientific tropes.
 British authors who have embraced this style have often published their work in mainstream literary magazines even after American pulp magazines became popular.
 Popular weird fiction writers included Edgar Allan Poe, William Hope Hodgson, H. P. Lovecraft, Lord Dunsany, Arthur Machen, M. R. James, and Clark Ashton Smith.
The Melingriffith Brass Band of the Melingriffith Tin Plate Works of Whitchurch, Cardiff, south Wales was one of the best known music ensembles in South Wales in the late 19th and early 20th century.
 It is also arguably Wales's oldest, originally established in 1798 as a Drum and Fife Band to "assist the recruitment of a Company of Volunteers to fight against the French, who were threatening to invade Britain."
 With the 13th Glamorgan Rifle Volunteers Corporation, in 1850 it became a full brass band and led by T.W. Booker and would practice in the New Houses, a row of workers cottages at the works.
 In the 1860s and 1870s the band was known as "Booker's Band" but it appears that the band was subject to splitting and by the 1880s and 1890s "The Volunteer Band", "The Temperance Band" and "The Drum and Fife Band" were known to exist until the Volunteer and Temperance bands merged to form "The Whitchurch Brass Band" as it became known in the early 20th century.
 In 1913, the Whitchurch Brass Band merged with the Melingriffith Cadet Corps.
 The band was led by Thomas James Powell from 1920 and in 1941 changed its name to the "Melingriffith Works Band".
 The headquarters were moved in 1937 from a small hall just above the works on Velindre Road to a building within the works between the River Taff and the Glamorganshire Canal.
 The band performed on Castle Street in June 1947 when the fifth Marquess of Bute ceded Cardiff Castle to the City of Cardiff.
Ecology is a new science and considered as an important branch of biological science, having only become prominent during the second half of the 20th century.
 Ecological thought is derivative of established currents in philosophy, particularly from ethics and politics.
 Its history stems all the way back to the 4th century.
 One of the first ecologists whose writings survive may have been Aristotle or perhaps his student, Theophrastus, both of whom had interest in many species of animals and plants.
 Theophrastus described interrelationships between animals and their environment as early as the 4th century BC.
 Ecology developed substantially in the 18th and 19th century.
 It began with Carl Linnaeus and his work with the economy of nature.
 Soon after came Alexander von Humboldt and his work with botanical geography.
 Alfred Russel Wallace and Karl Möbius then contributed with the notion of biocoenosis.
 Eugenius Warming’s work with ecological plant geography led to the founding of ecology as a discipline.
 Charles Darwin’s work also contributed to the science of ecology, and Darwin is often attributed with progressing the discipline more than anyone else in its young history.
 Ecological thought expanded even more in the early 20th century.
 Major contributions included: Eduard Suess’ and Vladimir Vernadsky’s work with the biosphere, Arthur Tansley’s ecosystem, Charles Elton's "Animal Ecology", and Henry Cowles ecological succession.
 Ecology influenced the social sciences and humanities.
 Human ecology began in the early 20th century and it recognized humans as an ecological factor.
 Later James Lovelock advanced views on earth as a macro-organism with the Gaia hypothesis.
 Conservation stemmed from the science of ecology.
 Important figures and movements include Shelford and the ESA, National Environmental Policy act, George Perkins Marsh, Theodore Roosevelt, Stephen A. Forbes, and post-Dust Bowl conservation.
 Later in the 20th century world governments collaborated on man’s effects on the biosphere and Earth’s environment.
The šajkača (Serbian Cyrillic: , ] ) is the Serbian national hat or cap.
 Traditionally worn by men in the Serbian countryside, it is named after Serb river troops known as "šajkaši", who protected the Austrian Empire against the Ottoman Turks in the 18th century.
 A popular nationalist symbol in Serbia since the beginning of the early 20th century, it is typically black, grey or green in colour and is usually made of soft, homemade cloth.
 It became widely worn by Serb men during the First Serbian Uprising and was a key component in the uniform of the Serbian military from the beginning of the 19th century until the end of the 20th century.
 Today, it is mostly worn by elderly men in rural communities.
Arlington's Great Meadows is a 183-acre meadow located adjacent to the Minuteman Bikeway in Lexington, Massachusetts.
 The meadow was once the site of a dairy farm and was also used to graze livestock and harvest crops.
 In 1871, Great Meadows was acquired by the town of Arlington, Massachusetts for use as a water storage area for the Mystic River.
 After being drained in the early 20th century, it turned into a protected area for wildlife.
 To this day, it also serves as a popular recreational area and an important piece in local flood control in addition to remaining a protected area.
The Angels of Mons is a popular legend about a group of angels who supposedly protected members of the British Army in the Battle of Mons at the outset of the First World War.