“The charge chamber needs a solid back when it’s fired,” Boomer said, tossing another bag on the pile. “Explosions seek the path of least resistance. We want that path to be straight up under the German trenches, not back down these galleries toward ours. We’re trying to break the German lines, not our own.”

Frederick rolled his sore shoulders. “Fine, but how many more rows of bags do we need?

“To be safe, we need the tamping to be one and a half times the distance of the solid ground we’re setting to break through, so keep hauling, boys.”

The crew finished tamping the mine the day before the attack. That evening, Mole returned to the dugout from a meeting with the other crews’ leaders at the command center.

“Is the mission still on?” Boomer asked.

With a frustrated groan, Mole rubbed his ears. “What?”

“Is the mission still on?” Boomer repeated louder.

“Yes,” Mole said, pouring himself a cup of lukewarm tea from the crew’s kettle. “British planes will bombard the German lines to camouflage the noise of the Allied tanks moving into position on our lines over the next two hours, and our infantry has been notified about the mission and will storm no-man’s-land and take the German trenches after the mines are fired. If all goes as planned, they should meet little resistance.”

“So our mission’s not so secret anymore?” George asked.

“Not to anyone except hopefully the Germans.” Mole drained the last drops of tea from his tin cup. “Though it won’t be a secret from them for much longer.”

“Are the other mines ready?” Boomer asked.

“General Plumer said the Germans withdrew from the area above the Birdcage mines. He ordered all four mines in that area be held in reserve and not fired, but the nineteen other mines are set to detonate. Zero hour is 3:10 A.M.”

“That’s going to be one hell of an explosion,” Boomer said.

“The largest the world has ever seen,” Mole said. “Before he dismissed us, Major-General Harington told us we may not make history tomorrow, but we’ll certainly change the geography.”

George glanced over at the empty bunks of their lost crew members. “Just wish Bagger and Bats were here to see it.”

Thomas nodded. “We have to make sure those mines blow, in their honor.”

Before Mole and Boomer left the boys to recheck the leads and fuses running from the Maedelstede Farm mine to the top of the gallery shaft, Mole pulled an envelope from his pocket. “I almost forgot, Mouse. This came for you.” He handed the envelope to Charlie. “Last day in the tunnels and one of you lads finally gets some mail from home. Better late than never, I guess.”

Charlie stared at the envelope for several minutes after the men left.

“Aren’t you going to open it?” George finally asked.

Charlie swallowed hard. “What if it’s bad news?”

“What if it’s good news?” Thomas replied. “Only one way to find out.”

Charlie tore open the envelope and pulled out a single sheet of folded paper, which he handed to Frederick. “Would you read it for me, please?”