A history of the crusades edited by Kenneth Meyer Setton (University of Wisconsin Press, 1969 -) is available online.

The History of the Crusades, published by the University of Wisconsin Press over a twenty year period beginning in 1969, was intended to serve as a collaborative and comprehensive treatment of the topic, ranging in time from the first 100 years of the Crusades to their ultimate impact on the histories of the Near East and Europe. The work is comprised of six volumes, each of which is included here in its entirety.
The browsable and text-searchable volumes include

• Baldwin, M. W. (ed.) / The first hundred years: volume I (1969)
• Wolff, R. L.; Hazard, H. W. (ed.) / The later Crusades, 1189-1311: volume II (1969)
• Hazard, H. W. (ed.) / The fourteenth and fifteenth centuries: volume III (1975)
• Hazard, H. W. (ed.) / The art and architecture of the crusader states: volume IV (1977)
• Zacour, N. P.; Hazard, H. W. (ed.) / The impact of the Crusades on the Near East: volume V (1985)
• Zacour, N. P.; Hazard, H. W. (ed.) / The impact of the Crusades on Europe: volume VI (1989)

The copyright of the material is held by the Board of Regents of the University of Wisconsin System, but materials may be copied freely by individuals or libraries for personal use etc.