Question: What was the original purpose of the medium to large sized German police dog? 

Context articles: Papilio xuthus
Proterovaginoceras
Police Dog Unit
Murex (disambiguation)
Chesapeake Bay Retriever
Enoplognatha
Police dog
Ironbridge Capital
German Shorthaired Pointer
Rottweiler

Papilio xuthus, the Asian swallowtail, Chinese yellow swallowtail or Xuthus swallowtail, is a yellow-colored, medium to large sized swallowtail butterfly found in northeast Asia, northern Myanmar, southern China, the Korean Peninsula, Japan (from Hokkaidō to the Yaeyama Islands), Siberia and the Hawaiian Islands.
 It was also recorded in the state of Arunachal Pradesh, India, in 2014.
Proterovaginoceras (Ancient Greek for "earlier shield horn") is a medium to large sized endocerid (endocone-bearing orthoconic nautiliod) from the Early and Middle Ordovician included in the family Endoceratidae.
The Police Dog Unit, (Abbreviation: PDU; ) established in 1949, is a specialist force of the Hong Kong Police under the direct command of the Special Operations Bureau.
 Its role is in crowd control, search and rescue and poison and explosive detection.
 In addition, the Police Dog Unit works in collaboration with other departments for anti-crime operations.
Murex is a genus of medium to large sized predatory tropical sea snails.
The Chesapeake Bay Retriever is a large-sized breed of dog belonging to the Retriever, Gundog, and Sporting breed groups.
 Members of the breed may also be referred to as a Chessie, CBR, or Chesapeake.
 The breed was developed in the United States Chesapeake Bay area during the 19th century.
 Historically used by area market hunters to retrieve waterfowl, it is primarily a family pet and hunting companion.
 They are often known for their love of water and their ability to hunt.
 It is a medium to large sized dog similar in appearance to the Labrador Retriever.
 The Chesapeake have a wavy coat, rather than the Labrador's smooth coat.
 They are described as having a bright and happy disposition, courage, willingness to work, alertness, intelligence, and love of water as some of their characteristics.
Spiders in the genus Enoplognatha are, for theridiids, medium to large sized.
 Like "Steatoda", they have a large colulus and a subspherical abdomen.
 Males usually have enlarged chelicerae.
A police dog, known in some English-speaking countries as a "K-9" or "K9" (a homophone of "canine"), is a dog that is specifically trained to assist police and other law-enforcement personnel.
 Their duties include: searching for drugs and explosives, locating missing people, finding crime scene evidence, and protecting their handlers.
 Police dogs must remember several verbal cues and hand gestures.
 The most commonly used breeds are the German Shepherd, Belgian Malinois and Rottweiler.
Ironbridge Capital is an Australian equity firm which provides equity for Australian and New Zealand businesses.
 It invests in buyouts and expansions of medium to large sized businesses.
 Ironbridge was founded in 2003 by Neil Broekhuizen, Paul Evans, Julian Knights and Greg Ruddock, who collectively own the company.
The German Shorthaired Pointer (GSP) is a medium to large sized breed of dog developed in the 19th century in Germany for hunting.
The Rottweiler ( or , ) is a breed of domestic dog, regarded as medium-to-large or large.
 The dogs were known in German as "Rottweiler Metzgerhund" , meaning Rottweil butchers' dogs, because their main use was to herd livestock and pull carts laden with butchered meat to market.
 This continued until the mid-19th century when railways replaced droving.
 Although still used to herd stock in many parts of the world, Rottweilers are now also used as search and rescue dogs, as guide dogs for the blind, as guard dogs and police dogs.