Question: What did the king known as "Edward Longshanks" and the "Hammer of the Scots" use Greenhill, Evesham for? 

Context paragraphs:
The Skystone: The Skystone is a historical fiction novel written by Jack Whyte, which was first published in 1992.  The story is told by a Roman Officer called Publius Varrus, who is an expert blacksmith as well as a soldier.  In the early fifth century, amid the violent struggles between the people of Britain and the invading Saxons, Picts and Scots, he and his former General, Caius Britannicus, forge the government and military system that will become known as the Round Table, and initiate a chain of events that will lead to the coronation of the High King known as Arthur.

Naram-Sin of Akkad: Naram-Sin (also transcribed Narām-Sîn or Naram-Suen, meaning "Beloved of Sin"; reigned c. 2254–2218 BC,) was a ruler of the Akkadian Empire, the third successor and grandson of King Sargon of Akkad.  Under Naram-Sin the empire reached its maximum strength.  He was the first Mesopotamian king known to have claimed divinity for himself, taking the title "God of Akkad", and one of the first (following the earlier Lugal-Anne-Mundu) to claim the title "King of the Four Quarters, King of the Universe".

Henry de Lacy, 3rd Earl of Lincoln: Henry de Lacy, 3rd Earl of Lincoln, Baron of Pontefract (c.1251 – February 1311) was an English nobleman and confidant of King Edward I 'Longshanks'.

Greenhill, Evesham: Greenhill is a hill just north of Evesham, Worcestershire and was part of the site of the Battle of Evesham.  In the battle, Simon de Montfort was defeated and killed on 4 August 1265.  King Henry's son, Prince Edward, later Edward I used it as his base in the battle from where he launched his attack on Simon de Montfort's forces which were gathered around Evesham Abbey.

Unfinished Northern Pyramid of Zawyet El Aryan: The Unfinished Northern Pyramid of Zawyet El Aryan, also known as Pyramid of Baka and Pyramid of Bikheris is the term Archaeologists and Egyptologists use to describe a large shaft part of an unfinished pyramid at Zawyet El Aryan in Egypt.  It is dated by mainstream scholars to the early or the mid-4th Dynasty (2613–2494 BC) during the Old Kingdom period.  The pyramid owner is not known for certain and most egyptologists, such as Miroslav Verner, think it should be a king known under his hellenized name, Bikheris, perhaps from the Egyptian "Baka".  On the contrary, Wolfgang Helck and other egyptologists doubt this attribution.

Edward I of England: Edward I (17/18 June 1239 – 7 July 1307), also known as Edward Longshanks and the Hammer of the Scots (Latin: "Malleus Scotorum" ), was King of England from 1272 to 1307.  He spent much of his reign reforming royal administration and common law.  Through an extensive legal inquiry, Edward investigated the tenure of various feudal liberties, while the law was reformed through a series of statutes regulating criminal and property law.  Increasingly, however, Edward's attention was drawn towards military affairs.

Battle of Evesham: The Battle of Evesham (4 August 1265) was one of the two main battles of 13th century England's Second Barons' War.  It marked the defeat of Simon de Montfort, Earl of Leicester, and the rebellious barons by the future King Edward I, who led the forces of his father, King Henry III.  It took place on 4 August 1265, near the town of Evesham, Worcestershire.

King's School, Worcester: The King's School, Worcester (also known as King's Worcester or KSW; locally as simply King's; archaically "Worcester Cathedral Grammar School" or "Worcester Cathedral King's School") is an English independent school refounded by Henry VIII in 1541.  It occupies a site adjacent to Worcester Cathedral on the banks of the River Severn in the centre of the city of Worcester.  It offers mixed-sex mainstream education that follows the UK National Curriculum to around 1,465 pupils aged 2 to 18.  At age 11, approximately two thirds of pupils join the senior school from its two junior schools, King's Hawford and King's St Albans, while others come from maintained schools in the city of Worcester and the surrounding areas that include Malvern, Redditch, Kidderminster, Evesham and Pershore.

Suktimati: Suktimati (Shuktimati, Sukti) was the capital city of the Chedi Kingdom in India.  It lay on the banks of the river Shuktimati flowing through Chedi.  It was built by a Chedi king known as Uparichara Vasu.  In the Mahabharata, it has been quoted that this river gave birth to twins (a boy and a girl) through its association with a mountain called Kolahala.  The river then gives the twins to king Uparichara Vasu.  King Vasu makes the boy the commander of his armies and marries the girl, Girika.

Peter of Aigueblanche: Peter of Aigueblanche (or Peter of Aquablanca; died 27 November 1268) was a medieval Bishop of Hereford.  A nobleman from Savoy, he came to England as part of the party accompanying King Henry III's bride Eleanor of Provence.  He entered the royal service, becoming bishop in 1241.  He then served the king for a number of years as a diplomat, helping to arrange the marriage of Prince Edward.  Peter became embroiled in King Henry's attempts to acquire the kingdom of Sicily, and Peter's efforts to raise money towards that goal brought condemnation from the clergy and barons of England.  When the barons began to revolt against King Henry in the late 1250s and early 1260s, Peter was attacked and his lands and property pillaged.  He was arrested briefly in 1263 by the barons, before being mostly restored to his lands after the Battle of Evesham.

Supporting paragraphs: Greenhill, Evesham Edward I of England
Answer: his base