Formal Alliances (v4.1)
he Correlates of War Formal Alliance data set seeks to identify each formal alliance between at least two states that fall into the classes of defense pact, neutrality or non-aggression treaty, or entente agreement. A defense pact (Type I) is the highest level of military commitment, requiring alliance members to come to each other’s aid militarily if attacked by a third party. As the labels imply, neutrality and non-aggression pacts (Type II) pledge signatories to either remain neutral in case of conflict or to not use or otherwise support the use of force against the other alliance members. Finally, ententes (Type III) provide for the least commitment and obligate members to consult in times of crisis or armed attack. Each alliance classifies the highest level of military support that an alliance member pledges to another alliance member. The data set provides the type, members, and appropriate dates of activity of each identified alliance.
Version 4.1 of the alliance data expands the original Singer and Small (1966) deffinitions of alliance types to include neutrality and non-aggression pacts separately. Neutrality pacts are now labeled as Type IIa alliances, and Non-Aggression pacts are labeled as Type IIb alliances. Alliance terms also distinguish between neutrality and non-aggression in the dyadic data.
In addition, the fourth version now differentiates between the overall alliance type and the terms of the alliance by specific member. In the alliance member list of data, for example, both the Singer and Small (1966) alliance type and the specific terms by alliance member are included. Only the terms operational for the specific dyad are included in the dyadic and direct-dyad data.
In any papers or publications that utilize this data set, users are asked to give the version number and cite the article of record for the data set, as follows:
Gibler, Douglas M. 2009. International military alliances, 1648-2008. CQ Press.
The original alliance data set was assembled in the 1960s under the auspices of the COW project and was initially discussed in:
Singer, J. David, and Melvin Small. 1966. "Formal Alliances, 1815-1939." Journal of Peace Research 3:1-31.
The data were extended in:
Small, Melvin, and J. David Singer. 1969. "Formal Alliances, 1815-1965: An Extension of the Basic Data." Journal of Peace Research 6:257-282.
Current Version: V4.1
On April 11, 2013 version 4.1 was released; it updates the alliance data by including two Israeli treaties that were not in the original data. On March 19, 2013, we released version 4.0 of the alliance data set. V4.0 extends the data coverage and adds other substantive changes as outlined below.
The data are formatted by member, by dyad, and by directed dyad.
Alliance Member Format:
The file named < alliance v4.1 by member.* > contains the alliance dataset distributed by member, with one observation for each alliance member initiation. Note that, if a member exits an alliance and then reenters the same alliance later, then that member will be included in the alliance twice, with the appropriate dates of membership included for each observation. The file named < alliance v4.1 by member yearly.* > includes an observation for each alliance member year.
Dyadic Terms Format:
The file named < alliance v4.1 by dyad.* > contains the alliance dataset distributed by dyad, with one observation for each dyadic alliance initiation. Note that, if a member exits an alliance and then reenters the same alliance later, then this will in ate the number of dyadic alliance initiations for each particular alliance. Alliance terms in the dyad may not be applicable to each country code. Users should consult the asymmetric variable to determine whether the alliance includes terms that only apply to certain members. Specific terms are listed in the directed-dyad format. The file named < alliance v4.1 by dyad yearly.* > includes an observation for each allied dyad-year.
The file named < alliance v4.1 by directed.* > contains the alliance dataset distributed by directed-dyad, with one observation for each directed-dyad alliance initiation. In this format the alliance terms include the specific promises made by ccode1 toward ccode2. The file named < alliance v4.1 by directed yearly.* > includes an observation for each allied directed-dyad-year.
A more detailed description of the data may be found in the release notes in the ZIP file below. The ZIP files contain the following files: