“It’s all right,” said Thor.

And the four-star immediately shouted, “It’s all right, soldier. Stay at your post.”

The tank rumbled on, going through some maneuvers, with Alf walking directly behind it, his hand on the back almost as if he was pushing a six-year-old who had just got the training wheels taken off his bike.

“This is so…” But the driver saw the hard look in the four-star’s eyes, and fell silent.

The tank stopped. The engine stopped.

Then it started again.

Then stopped again.

Buck had never heard the engine of the M1A3 stop and start so cleanly. In fact, as he listened he thought the engine sounded cleaner and smoother. Less rumble and roar, more hum. More like music.

Alf stepped back away from the tank. It started to rotate swiftly on its axis, a maneuver that was hard to learn, since it required perfect balance between the left and right tracks. And the turret rotated the opposite direction so perfectly that to the observers it seemed not to be moving at all, as the tank moved under it.

Then the direction of movement changed abruptly. Alf stood with his hands in his pockets, watching. And then not watching, as the tank sped up and began to make a wide circle across the pavement. Faster. Faster. The M1A3 was not supposed to go at full gallop like this during training—it caused too much damage to the equipment. It was something you did only in combat, knowing that the mechanics would work it over before you had to take it into combat again.

The circle grew tighter, spiraling inward, as the tank began to move faster than Buck had ever seen any tank move. The tracks’ tolerances had long since been passed. But nothing seemed to be going wrong.

Once again, the tank headed directly toward Alf, this time at a breakneck speed. Once again, it came to an abrupt stop right in front of him.

The whole crew poured out of the tank, some of them rubbing their heads or limping a little. They were expostulating in highly colorful language.

“Attention!” Buck called.

They looked at him, recovered their composure, stood at attention.

“I see some of you rubbing your heads,” said Buck. “Were you wearing your helmets?”

“No, sir,” two of them answered at once.

“And here I thought you were a well-disciplined crew,” said Buck mildly.

“We didn’t know she was going to move, sir!” said the tank commander.

“How did she move?” murmured the driver.

“I think she moved very well indeed,” said the four-star, in a tone that suggested it was the final comment in this conversation.

“Get back in your castle, boys,” said Buck. “Nobody gave you permission to come out.”

“No,” said Alf casually. “We won’t need them inside for a while.” He strode to his wife. “Well, Gerd, did you get what you needed?”