English, included scientifi c, philosophical, theological,
and pastoral treatises. His theological works included the
Hexaemeron (1230s) and numerous biblical commentar-
ies and sermons. He wrote important commentaries on
Aristotle’s Posterior Analytics and Physics and trans-
lated the Nicomocheon Ethics from Greek into Latin. His
scientifi c interests were refl ected in books on astronomy,
comets, the tides, mathematics, and the rainbow.
As a bishop with a strong sense of pastoral responsi-
bilities Grosseteste was an important fi gure in the reform
movement in the 13th-century church; his devotional
treatises were infl uential and widely read. While he
supported the doctrine of papal plenitude of power, he
clashed with the papacy over the growing practice of
papal provisions (direct papal appointment of ecclesi-
astical personnel) and attacked corrupt papal politics
at Rome in 1250.
Robert Grosseteste died on 9 October 1253. His
books and notes were bequeathed to the Franciscan
library at Oxford, ensuring his continuing scholarly
infl uence on later generations of Oxford scholars.
See also Bacon, Roger
Further Reading
Callus, Daniel A., ed. Robert Grosseteste: Scholar and Bishop.
Oxford: Clarendon, 1955
Crombie, A.C. Robert Grosseteste and the Origins of Experimen-
tal Science, 1100-1700. Oxford: Clarendon, 1953
Southern, R.W. Robert Grosseteste: The Growth of an English
Mind in Medieval Europe, Oxford: Clarendon, 1986.
GUESCLIN, BERTRAND DU
(ca. 1320–1380)
Constable of France. Bertrand du Guesclin, perhaps the
most famous French warrior of the Hundred Years’ War,
was the fi rst of three distinguished Breton noblemen to
serve as constable of France during this confl ict. Du
Guesclin was born into an old but not very wealthy fam-
ily. In 1353, he succeeded his father as lord of Broons
and a year later was knighted. He began serving the
French crown at Pontorson as early as 1351, and for
the next thirteen years his military career was confi ned
to Normandy, where he fought for the king against the
supporters of Charles the Bad, king of Navarre, and Brit-
tany, where he fought for Charles de Blois against Jean
de Montfort, the English-backed claimant to the duchy.
In 1357, he led the forces that supplied the besieged city
of Rennes. In May 1364, he won a great victory over
the Navarrese forces at Cocherel in Normandy after
feigning a withdrawal that induced his foes to abandon
a superior position. In the same period, he also suffered
defeats, as the English captured him at Pas d’Évran in
1359, at the bridge of Juigne in 1360, and at Auray in- In this last battle, Charles de Blois was killed and
Montfort became duke of Brittany.
With Normandy and Brittany now pacifi ed, Du Gues-
clin devoted the rest of the 1360s to service in southern
France and Spain. Louis of Anjou, brother of Charles V,
was royal lieutenant in Languedoc and needed him to
lead numerous routiers (unemployed soldiers) outside
the realm on campaigns in Provence and Castile. His
successful expedition to Spain in 1365 was followed by
his defeat and capture at Nájera in 1367. In 1369, how-
ever, he returned to Spain and reinstalled a pro-French
king on the Castilian throne.
Rarely successful at pitched battles, Du Guesclin was
adept at handling bands of routiers and fi ghting with
their tactics. In 1370, when a routier chieftain, Robert
Knolles, was leading an English raid into northwestern
France, Charles V summoned Du Guesclin and made
him constable. The latter then made a private alliance
with Olivier de Clisson, a wealthy Breton lord who had
fought against him at Auray and Nájera. Clisson brought
powerful contingents of Bretons into the French army,
and he and Du Guesclin conquered Poitou and Saintonge
in 1371–72. In 1373, they secured Brittany, whose duke
had gone over to the English.
For the next fi ve years, the constable led French
forces against the English in various parts of France. At
the end of 1378, Charles V made the political error of
trying to confi scate Brittany. Du Guesclin, one of those
charged with implementing this unpopular decision,
was reluctant to do so, since many of his old comrades
had rallied to the duke. Never popular with the king’s
nonmilitary advisers, he was nearly removed from offi ce
but instead was sent to fi ght against routiers in Auvergne,
where he died from an unknown illness (perhaps dysen-
tery) in the summer of 1380 while besieging the town
of Châteauneuf-de-Randon.
Admired by his contemporaries for his military prow-
ess, Du Guesclin earned the titles count of Longueville
and duke of Molina. He was buried at Saint-Denis.
See also Charles II the Bad; Charles V the Wise
Further Reading
Cazelles, Raymond. “Du Guesclin avant Cocherel.” Actes du
Colloque International de Cocherel (1964): 33–40.
Dupuy, Micheline. Bertrand du Guesclin: capitaine d’aventure,
connétable de France. Paris: Perrin, 1977.
Hay du Chastelet, Paul. Histoire de Bertrand du Guesclin, con-
nétable de France. Paris: Billaine, 1666.
Jacob, Yves. Bertrand du Guesclin, connétable de France. Paris:
Tallandier, 1992.
Luce, Siméon. Histoire de Bertrand du Guesclin et de son époque.
Paris: Hachette, 1876.
John Bell Henneman, Jr.GUESCLIN, BERTRAND DU