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THE POLITICAL CRUSADES 
OF THE THIRTEENTH 
CENTURY 
 hat is a political crusade? In one sense, of course, every crusade is political,
for every crusade aims at conquest, at replacing the rule of unbelievers
by that of Christians. But there is an obvious difference between a crusade
against the Saracens — or even against the Albigensians — and
a crusade against Manfred or Peter of Aragon. In the first case, political
means are being used for a 
 The political crusades are so closely connected with the general history
of the thirteenth century that a complete bibliography would be impossibly
long. The most important docu ments are in the papal registers. Those of
Innocent III were edited by Bréquigny and reprinted in Migne; the
registers of most of the other thirteenth-century popes have been published
by the Ecoles françaises d'Athènes et de Rome. J. L. A. Huillard-Bréholles
published the acts of Frederick II and his sons in the Historia diplomatica
Friderici secundi (7 vols. in 2, Paris, 1852-1861). J. F. Böhmer, Regesta
imperii, V: Die Regesten . . . 1198—1272 (ed. Julius Ficker, 2 parts,
Innsbruck, 1881-1882) contains useful material, especially for the period
after 1250. The MGH for this period give not only important chronicles, but
also some collections of documents such as the Constitutiones et acta publica
imperatorum (Legum Sect., IV), and the Acta pacis ad S. Germanum anno MCCXXX
initae (Epistolae selectae, IV). Italian chronicles may be found in the MGH
or in Muratori, RISS. The important life of Innocent IV by Nicholas of Carbio
(or Curbio) was first published by Muratori (RISS, III); there is a better
edition by Pagnotti in the Archivio della Societa romana di storia patria,
XXI (1898). English chronicles are in the Rolls Series; of these, Matthew
Paris is especially impor tant for the documents given in his Additamenta
(vol. VI of the Rolls Series edition). French chronicles are printed in the
RHGF; this series also includes useful documents, especially on the crusade
of 1285. The Layettes du trésor des chartes and Winkelmann's Acta
imperii inedita (Innsbruck, 1880—1885) contain less than might be expected.
The same may be said of the documents of the Angevin kings edited by G. Del
Giudice, C. Minieri Riccio, and G. Silvestri. There is some useful material
in I. Carini, Gli Archivi e le biblioteche di Spagna, in rapporto alla storia
d'Italia in generale e di Sicilia in particolare (Palermo, 1884—1897).
Finally, the letters of Albert von Beham, edited by C. Höfler (Bibliothek
des litterarischen Vereins in Stuttgart, XVI, 1847) throw some light on German
affairs in the 1240's. 
 The only book which gives a general survey of material covered in this chapter
is H. Pis sard, La Guerre sainte en pays chrétien (Paris, 1912), and
Pissard is more concerned with the development of canonical doctrine than
with the details of the crusades. In spite of its title, O. Yolk's Die abendlandisch-hierarchische
Kreuzzugsidee (Halle, 1911) refers to our topic only occasionally. It does
discuss the inchoate political crusades of the eleventh century, and for
this problem P. Rousset, Les Origines et les caractères de la premiere
croisade (Neuchâtel, 1945) and C. Erdmann. Die Entstehung des Kreuzzugsgedankens
(Stuttgart, 1935) should also be consulted. E. Jordan, L'Allemagne etl'Italie
au XII6 et XIIIe siecles (Paris, n.d.) and K. Hampe, Deutsche Kaisergeschichte
in der Zeit der Salier und Staufer (Leipzig, n.d.) are both excellent 
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