I am doing a personal project and was attempting to find information on defensive pacts throughout history. From wikipedia, one gets the impression that the first defensive pact was the Dreikaiserbund.
In popular game titles like Civilization 5 and the Total War series, defensive pacts appear long before recent history. In the same titles, a defensive pact differs from a military alliance in that defense pact bound countries will automatically declare war only if the other member of the pact has war declared on them, whereas a military alliance works as either the aggressor or defender.
When did these alliances begin and what is the earliest example, if not the Dreikaiserbund?
Thanks!
The concept goes back at least to Classical Greece (5th and 4th centuries BC). Treaties of alliance between Greek city-states tended to be defensive only. They promised that the two states were to have "the same friends and enemies", but stipulated that they were required to help each other only if they were attacked. They did not commit the states involved to supporting each other's offensive campaigns:
An alliance with Kerkyra was decided on, with certain reservations. It was to be a defensive, not an offensive alliance. It did not involve a breach of the Thirty-Year Truce with the Peloponnese: Athens could not be required to join Kerkyra in any attack upon Corinth. But each of the contracting parties had a right to the other's assistance against invasion, whether of his own territory, or that of an ally.
-- Thuc. 1.44.1
In a few cases, ancient sources report the actual terms of alliances, and these usually reveal their defensive nature:
The Terms of the Alliance between Athens and Sparta, 421 BC
- The Lakedaimonians shall be allies of the Athenians for fifty years.
- Should any enemy invade the territory of Lakedaimon and injure the Lakedaimonians, the Athenians shall help them in such way as they most effectively can, according to their power. But if the invader be gone after plundering the country, that city shall be the enemy of Lakedaimon and Athens, and shall be chastised by both, and one shall not make peace without the other. This to be honestly, loyally, and without fraud.
- Should any enemy invade the territory of Athens and injure the Athenians, the Lakedaimonians shall help them in such way as they most effectively can, according to their power. But if the invader be gone after plundering the country, that city shall be the enemy of Lakedaimon and Athens, and shall be chastised by both, and one shall not make peace without the other. This to be honestly, loyally, and without fraud.
- Should the slave population rise, the Athenians shall help the Lakedaimonians with all their might, according to their power.
-- Thuc. 5.23.1-4
This is how states would normally make treaties with each other on an equal basis. The Greeks did not willingly agree to an offensive alliance. If, however, there was a clear imbalance of power, the stronger of the two states involved in making a treaty would generally impose an offensive alliance on the weaker. It would not commit itself to offensive support, but would require it of its inferior ally. This was the privilege of hegemonic states. Sparta, for example, stipulated in all treaties with the unequal allies of the Peloponnesian League that they were to "follow wherever the Spartans may lead", but only promised to help those allies if they were under direct attack.
In short, the full military alliance you find in games like Total War was extremely rare in Classical Greece - it existed only between states that were either extremely close or extremely keen to fight a common enemy. Most alliances were actually defensive or half-defensive, with the superior state refusing the obligation to provide offensive support.
There's a nice overview of the kind of treaties known from Ancient Greece in Hans van Wees' Greek Warfare: Myths and Realities (2004), 12-15.