And this was victory. The ground was strewn with the curiously alien corpses. The chemical reaction left them bleeding some strange blue blood—Jo was quite certain that it was blood despite her complete ignorance regarding their physiology—and emitting an odor that somehow managed to put her in mind of the stench of death and decay while not actually resembling it. Her nose twitched involuntarily.

"Come along, Miss Grant," smiled the Brigadier. "We have supplies in the jeep, get that smell out of your nose. Coming Doctor?"

The Doctor waved him back. He was standing still, taking in the scene with the kind of calm that could not be mistaken for serenity. "They didn't mean any harm," he said finally. "They just didn't understand. If only we could have found a way to communicate…"

The Brigadier nodded. "Quite unfortunate, yes. Unfortunate to be sure but at least nobody was hurt. Not a single man lost."

"Quite a few were injured, snapped the Doctor angrily. "Life doesn't lack value just because it happens to have a different species. Or skin color." That last was intended to provoke.

And provoke it did. "Look, Doctor. I appreciate your assistance, I truly do. But there were lives at stake here. You don't start crying about bacteria…"

"These people are not bacteria…"

"when you wash your face. They wouldn't have stopped. The whole city would have died. It's quite impressive none of my men died. And I will not apologize for being glad they didn't. I'm sorry we couldn't get you your perfect solution but the ends justifies the means."

"The ends justify nothing," the Doctor, spat back. "Such a pathetic little phrase easily shaped to prop up every monstrous atrocity in your pathetic human history. So easy salve the conscience of wars and genocides with the handy excuse that it had to be done."

"But it did have to be done."

"Convenient," said the Doctor wryly.

"No it is not convenient," huffed the Brigadier. "But it was necessary."

The Doctor let that hang in the air a moment. "You're right. Nothing about this was convenient."

There was another minute, then Jo asked, "What did you mean the ends doesn't justify the means. I mean, if everything turns out okay in the end…"

"Well that's just it, Jo," said the Doctor more calmly. Jo had a knack for bringing out his calmer side. "The ends don't justify the means because the ends are not, in fact, the end."

The Brigadier laughed. "I think you will find that by definition…"

"You get the opportunity to kill Hitler before he takes power," The Doctor interrupted. "You know he will bring war and holocaust and myriad strife. Do you kill him?"

"Kill Hitler? Of course!"

"And your murder is okay because the end is just. Only it's not the end. Germany is still going through the same struggles. The despair and disaster growing from the wake of the First World War which Hitler exploited are still in evidence. The fears and prejudices Hitler used are still very much present and someone else plays on them instead. Many of Hitler's advisors are still in place. Everything you tried to prevent still happens—more viciously now that they have a martyr." The Doctor stopped, subtly shifting from righteous crusader to crusty professor mode. "Time flows and evolves in unpredictable patterns. There are always, always unforeseen consequences. The ends are too ephemeral to justify anything. The means must be justified on their own merits."