A march (march(i)a) is a militarised frontier, and was used in this sense in Europe from the late eighth-century onwards, so under the Norman (ie. William the Conqueror onwards) and Angevin (ie. Henry II onwards) rule numerous marches had appeared. The first and earliest was the Welsh Marches (there is a semantic discussion about whether it is March or Marches), which were practically established in the late eleventh-century but really not identified as such until nearly a century later. There have been arguments made for considering the Normandy border a march, likewise in Ireland beyond the Pale of Dublin and around Waterford, and in the mid thirteenth-century the English and Scottish kings agreed a march between their borders.

So why might historians refer chiefly to the Marcher lords of Wales rather than to the various other frontiers of Anglo-Norman society?

The answer is fairly simple.

1. The Welsh Marches are the oldest and first to be identified (contemporaneously) as March' Wallie.

The Marches began their life as several conquest lordships on the western fringe of William's English realm. While 'March' appears in Domesday these were less official territories but simply holdings which overlapped with a geographical region which constituted 'the valleys of of the river Lugg and of the Hindwell Brook' (Liebermann, 2010, p.6). The term only began readily used in the more traditional sense in the 1160s when sheriffs began reporting to the Exchequer for expenses and duties accrued explicitly 'to guard the March of Wales' (ad custodiendam March’ Walie).

Thus historians referring to the activities of 'Marchers' in this time period (and really up to the mid thirteenth-century) will likely be referring to lords possessing lands along the medieval March of Wales, but why would historians consistently need to refer to this place?

For more information see:

Lieberman, M., The Medieval March of Wales: The Creation and Perception of a Frontier, 1066-1283, (Cambridge, 2010).

2. Political and Social Context (up to 1284)

The Welsh border was a particularly contested one. The Norman and Angevin invasions did not culminate in a 'conquest' until the Edwardian wars of 1277-8 and 1282-3. In this period the Welsh rulers had been thorns in the sides of English hegemony over Britain and the Welsh Marchers were granted particular exemptions and privileges for maintaining peace along the border (although one of those exemptions included not being bound by peace agreements between the Welsh rulers and the English Crown). The Welsh rulers and the Marcher lords played a not unimportant role in English political history (even excluding the plethora of 'failed' conquests). The Marchers were to feature prominently in Magna Carta, the revolt of Richard, earl of Cornwall, the Baronial Movement (under Simon de Montfort). They were fairly major players, even at this early stage, and things were only going to get worse (or better, depending on your point of view).

For more information see:

Carpenter, D.A. The Struggle for Mastery: The Penguin History of Britain, 1066-1284, (London, 2004).

Davies, R.R., Age of Conquest: Wales, 1063-1415, (Oxford, 2000).

Holden, B., Lords of the Central Marches: English Aristocracy and Frontier Society, 1087-1265, (Oxford, 2008).

3. Who were the medieval Marchers?

While the 'founding' members of the Marches were chiefly provincially powerful but really only marginal members of the Norman aristocracy, as the thirteenth-century progressed the Marchers began increasingly important and powerful. The list of original families should be fairly familiar to anyone with some knowledge of English history up to 1284:

Mortimers of Wigmore; Corbets of Caus; the Braose, who constructed a rather large 'empire' by 1200; Fitzalans of Oswestry and Clun; Clares of Glamorgan, Newport, Caerleon and Usk.

These were really five power powerful Marcher families (some dating back to the Norman Conquest, others to the reign of Henry I). However, over the course of the thirteenth-century failures to produce male heirs and royal policy substantially changed the composition of the lords of the Marches. Families which failed in the male line included: Braose (1230), Lacy (1241), Marshal (1245), fitz Baderon of Monmouth (1257), Clifford (1263), Chaworth (1283) and Cantilupe (1283).

By 1284, only eight of the twenty-four barons of the Marches had a history which stretched beyond 1200. Most of the rest had only been associated with the March since 1240.

From the late twelfth-century the political importance of members of the March had steadily increased. John, later king of England, had married into Marcher stock when he wed Isabella of Gloucester; William Marshal, later regent of England, was earl of Pembroke from 1199; Richard Plantagenet married William's daughter Isabel Marshal, thus assuming territories in Gloucester in 1225; Henry III installed his brother Edward as lord of Carmarthen and Cardigan in the 1250s; and the Edwardian (ie. Henry III's son's) Conquests led to the establishment of numerous new conquest lordships within Wales (the only major Welsh kingdom to survive essentially intact was Gruffudd ap Gwenwynwyn of Southern Powys - Powys having fragmented in the 1160s).

TL:DR: As Rees Davies puts it: ‘in 1200 only one English earl, the Earl Marshal, held large estates in the in the March; by 1307 seven out of the ten earls of England were lords of the March. The March had become clearly the land of the top people, the top people of English politics.’ (Davies, 1979, p.39).

The Marchers remain a prominent feature of English history simply because they were prominent members of English society. Historians refer the Marchers generally mean the Welsh Marchers because they were a clearly self-identifying 'corporation' who shared interests and actively campaigned together during periods of instability. They possessed legal and practical exemptions and constituted at various periods either real political power through said solidarity or through their participation at the highest echelons of medieval English politics.

For more information see:

Davies, R.R., Lordship and Society in the March of Wales, 1282-1400, (Oxford, 1978).