But after a week of climb-downs, the rank-and-file Greens drew a line in the sand yesterday, rebelling against their leaders' newly discovered militarism. Their leaders had agreed that if necessary the Serbs could be bombed, even by the Luftwaffe.
But even this uprising, rendered devoid of meaning after Nato's agreement with Belgrade, was less debilitating than expected.
Joschka Fischer, the party's leader and now certain to become Germany's next foreign minister, had managed to persuade 28 of his 48 members in the outgoing parliament to back Germany's participation in any punitive mission against the Serbs. Only nine Greens voted against, and another eight abstained. Despite being given a free vote, the majority of the parliamentary party endorsed Mr Fischer's tightrope act.
The vote marks the heaviest defeat yet for the Greens' "Fundi" wing. Their leader, Ludger Volmer, had urged his colleagues to resist authorising Nato action in Kosovo, which he said would be "in contravention of international law".
Yesterday, the Greens and Germany with them crossed the Rubicon. After the refusal to participate in the Gulf War, and its very late arrival on the Balkan scene, Germany now seems ready to play as full a part in Nato as any other normal member.
The climbdown over Kosovo also illustrates how quickly the Greens have been shedding their ideological baggage in their rush to reach the highest offices of Germany.
Less than three weeks ago, when they found themselves in negotiations for government posts after the Social Democrats' stunning electoral triumph, the Greens were clutching a long list of demands. Almost all have been either watered down, or tossed into the waste-bins.
Walking the thin dividing line between compromise and cave-in, Mr Fischer has found himself pushed systematically towards the latter.
So smoothly have the coalition talks been proceeding from the Social Democrats' point of view, that Gerhard Schroder, the future Chancellor, has had more trouble containing the ambitions of his colleagues than those of the Greens.
As the negotiations continue into the weekend, it is already clear that most of the Green booby-traps have been defused. Thus, on motorway speed limits, a cause very close to Green hearts, there appears to be no compromise in sight. Mr Schroder said "no speed limits", and it looks as though there will be none.
The Greens will be given the Health Ministry, but no cannabis will be available, with or without prescription.
And on the life-and-death question of nuclear power, Mr Fischer's team extracted a mighty fudge from their coalition partners. The "Fundis" wanted the immediate closure of some nuclear plants. The "Realos", led by Mr Fischer, expected, at the very least, a set timetable for closures, beginning in the life-time of the new parliament. What they got in the end was a one-year moratorium, during which negotiations are to be conducted with the nuclear industry. After that, they will have more talks about setting deadlines for the 19 plants that supply one-third of Germany's electricity.
Jurgen Trittin, the Greens' Environment minister, suggested that some power plants will be phased out in the next four years, but he appears to have received no cast-iron guarantees to that effect.
The Greens were also forced to sacrifice some of their dreams of granting German nationality to children of Germany's long-term foreign residents. Under the deal reached, the automatic right will be extended only to the third generation of immigrants, although even that, with the easing of nationalisation rules, will create up to three million German "foreigners". Although this agreement is exactly on the Social Democrats' terms, the Greens are happy to present it as a "compromise".
Whether Mr Fischer can sell the entire package to his more militant grassroots will be seen next weekend, when the Greens hold an emergency conference. But so far he has got away with it, and there is every indication that the "Realos" are in the ascendancy.