Excerpt
A writer and philosopher of the late twentieth century once said, "Space is big." There are three well-known corollaries to this. The first is that the number of planets where biological accidents occurred in the correct order to create life is small. The second is that the number of planets where life managed to overcome odds and achieve sentience is smaller still. And the third is that many of these sentient life-forms blow themselves into extinction before they ever make it off their planet of origin.
If space is big and mostly uninhabited, it should be safe to assume that any life-forms who really didn't get along could avoid spending time in each other's company.
Unfortunately, the fact that said life-forms could avoid each other doesn't necessarily mean that they would.
When the Others attacked systems on the borders of Confederation territory, Parliament sent out a team of negotiators to point out that expansion in any other direction would be more practical as it would not result in conflict. The negotiators were returned in a number of very small pieces, their ship cleverly rigged to explode when it would do the most damage.
The Confederation found itself at a disadvantage. Its member races had achieved an interstellar presence only after they'd overcome the urge to destroy themselves or any strangers they ran into. Evidence suggested the Others had flung themselves into space without reaching this level of maturity. Clearly, in order to survive, the Confederation would have to recruit some more aggressive members.
Humans had a bare-bones space station and a shaky toe-hold on Mars when the Confederation ships appeared. Some fairly basic technology by Confederation standards, combined with the information that the Others were heading Earth's way, convinced humanity to throw its military apparatus into space where they took to interstellar warfare the way the H'san took to cheese.
Some one and a half centuries of intermittent war later, borders had shifted, and Humans had been joined by first the di'Taykan and then the Krai. Much of the military terminology introduced into the Confederation's common tongue remained Human although, as the three races became increasingly more integrated, di'Taykan and Krai words began creeping in. The Krai, for example, had sixteen useful adjectives describing the impact of an antipersonnel weapon on a soft target.
Although the induction of younger and more aggressive species had undeniably solved the problem presented by the Others, it had also irrevocably changed the face of the Confederation. Feeling just a little overwhelmed, many of the original species spent their spare time sighing and reminiscing about the good old days.