Stephen Ressler, P.E., Ph.D.Professor EmeritusU.S. Military Academy at West Point

Introduction

Education: B.S. – U.S. Military Academy at West Point (1979)

M.S.C.E. & Ph.D. – Lehigh University

Master of Strategic Studies – U.S. Army War College

Professional: Commissioned officer, Army Corps of Engineers

Deployments to Somalia and Afghanistan

Professor of Civil Engineering, USMA

Retired from active duty in 2013

Scholarly Interests: Structural engineering

Engineering education

Engineering in the ancient & medieval worlds

The Great Courses

https://www.thegreatcourses.com/

HOMEWORK #1:The Great Bridges Scavenger Hunt

• Lecture #3: “A Field Guide to the Great Bridges of Bright Horizons 38 & Times Journeys 17”

• The 18 bridges in this handout will be addressed in the lecture.

• YOUR MISSION: Visit as many of these bridges as possible at our upcoming ports of call.

Win fabulous prizes!

HOMEWORK #2:Discovery Learning

• If you see a particularly interesting bridge that isn’t in the “Scavenger Hunt” handout, e-mail me a photo no later than August 21st.

• I will integrate your bridge into Lecture #3.

My e-mail: sjressler@gmail.com

Stephen Ressler, P.E., Ph.D.Professor EmeritusU.S. Military Academy at West Point

The Medieval Castle

• Private fortified residence of a lord or noble

• Etymology: castrum → castellum → castel→ castle

• Purposes:• Defend key terrain or route

• Pacify and control a region

• Base for offensive operations

• Administrative center

• Symbol of power

Origins

• Breakdown of the Carolingian Empire (late 9th century)

• Attacks by Vikings, Muslims, and Magyars

• Influenced by:

Celtic oppida Roman and Byzantine fortifications

The Walls of Constantinople

The Motte and Bailey Castle

motte

keep(donjon)

bailey

palisade

moat

bridge

palisade

The Motte and Bailey: An Evolving Technology

• Developed in the 10th century

• Closely tied to feudal society

• Easy to build with unskilled labor

• Effective against unsophisticated enemies

• Built throughout France, Holy Roman Empire, British Isles, Denmark, and the Low Countries

• Many local variations

• Timber structures gradually rebuilt in stone

• Became obsolete in the 12th-14th centuries Launceston Castle, Cornwall, England(11th-12th century)

Stimuli for Change

Advances in stone masonry The Crusades

Advances in siegecraft

Medieval Siegecraft

• Treachery

• Investment (blockade)

• Escalade

• Siege towers

• Battering rams

• Artillery (catapults)

• Mining

Medieval Artillery

Ballista

Onager

Trebuchet

Medieval Artillery: How it Worked

Video clip from “Do It Yourself Engineering,” produced by The Great Courses

The New Paradigm: Carrickfergus Castle

The largest and best-preserved Norman castle in Ireland

Carrickfergus Castle

Belfast

AntrimCoast Scotland

Giant’sCauseway

CarrickfergusCastle

NorthChannel

Belfast Lough

Carrickfergus: A Tumultuous History

• 1177 – Castle built by John de Courcy as a base for his conquest of Ulster

• 1204 – de Courcy ousted by Hugh de Lacy acting on behalf of King John

• 1210 – Castle captured by King John; de Lacy exiled

• 1216 – Castle expanded by order of the Crown

• 1226 – Hugh de Lacy returns; further expands the castle

• 1315 – Richard de Burgh implements improvements to gatehouse

• 1315-16 – Siege by Scottish army under Edward Bruce

• 1556-1820 – Major modifications to accommodate artillery and to incorporate the castle with the town walls

Phase I

Phase II

Phase III

Phase IV

PhasesV-X

Carrickfergus: Phases I-IV

Sketchup Model

Let’s build a castle!

The Norman Castle: Major Components

keepinner ward

curtain walls

great hall

middle ward

outer ward

gatehouse

projectingtowers

postern gate

Castle Design: The Big Picture

• Location:• Strategic control of Belfast Lough• Water on three sides; a natural harbor• Spring for water supply

• Concentric design:• Succession of mutually supporting defensive

lines—ditch, gatehouse, towers, curtain walls, inner and outer wards, keep

• Oriented toward the most dangerous approaches

• Adapted to the local terrain

• Projecting towers to cover curtain walls

Defensive Features: Details, Details, Details • Curtain walls:

• Crenellations• Wall walk• Hoardings• Machicolations• Arrow loops

• Gatehouse• Drawbridge• Portcullis• Murder hole

• Keep• Windows• Stairways• Latrines

• Postern Gate

Every detail has a purpose!

Cahir Castle

Curtain Walls: Crenellations & Wall Walk

Embrasures for cannon(added in 16th century)

Hoardings & Machicolations

Carcasonne Cahir Castle

Arrow Loops

Carrickfergus Ferns Castle Ferns Castle

Defensive Features: The Gatehouse

Projectingcirculartowers

Portcullis

Drawbridge

Machicolation

Inward-facingarrow loops

Drawbridge & Portcullis

Murderhole

Roscrea Castle

Trim Castle

Lifting Apparatus

Roscrea Castle Cahir Castle

The Keep

Staircases

Carrickfergus Castle Ferns Castle Cahir Castle

Latrines

The Postern Gate

QUIZ: Siege Methods vs. Defensive Measures

• Investment

• Escalade

• Siege towers

• Battering rams

• Artillery

• Mining

Siege Methods

Sortie

Countermining

Artillery

Defensive & Active Measures

Large supply of food & water Small garrison

High walls TowersMoat Crenellations Machicolations Arrow loops

High walls TowersMoat Crenellations Arrow loops

Thick walls Machicolations

Moat

Moat

Thick walls

Thick walls

Concentricdesign

Sortie

Sortie

Build on bedrock

Towers

Sortie

Variations on a Theme: Trim Castle

Barbican Gate & Battered Walls

Batteredwalls

Barbican Gate

Battered Walls

More Variations

Nenagh Castle, IrelandRoscrea Castle, Ireland

The Castle and Feudal Society

• Local protection from external invaders, following the breakdown of central authority

• A reflection of the persistent medieval struggle between king and aristocracy:

• Royal castles – Used to impose control on the nobility

• Baronial castles – A local hereditary power base, independent of central authority

• Basis for the control of local populations, towns, fields, mills, forests, toll roads

• Garrisoned by the lord’s vassals

• Often enclosed and protected a church

• Served as a stimulus for economic development

“The strong built castles, the weak became their bondsmen.”

Medieval Technological Development

• Warfare as a stimulus for technological development

• The quintessential arms race—castle vs. siegecraft

• Interplay between military and civil technologies

• Increasing complexity and scale →escalating costs → centralization of political power

• Role of disruptive technologies

Carrickfergus in the Gunpowder Era

Questions?