Defenders might sometimes dig counter-tunnels in order to reach the enemy's mines and launch an attack; frequently thermal weapons were used to drive the besiegers from the tunnels.
To scale that up, Trump's border wall will need 51,200 towers and 10.7 million people to perform its various chores: pouring hot oil and dropping rocks on invaders, pushing away their ladders, firing flaming arrows, digging counter-tunnels to intercept invaders' tunnels and pulling ropes to operate the torsion catapults.
He was the brains behind a lot of what the team does but, as has happened before when we've lost players, we'll have to dig deep to counter that and we're confident in our squad these days.
The townspeople have no idea whether the explosion was an accident or an attack, but they dig out Geiger counters, clean out underground shelters and leaf through cold-war-era instruction manuals about the A-bomb.
Threaded throughout the evening is Mr. Daisey's funny-scary guided tour of the city of Los Alamos, where trinkets memorializing the bomb are sold at gift shops, and tourists with Geiger counters dig around in the sand, illustrating how much radiation can be found just a few inches underneath the ground.
It's where you can sit with your elbows on a counter and dig into one of the best burgers in the city, and a slice of pie.
Even though the government has superiority on the ground and in the air, its forces have also taken to digging tunnels, to counter the rebel strategy.
But you don't have to dig very deep to find the counter-point.
Easterners are more likely to see both sides of a conflict when faced with counter-arguments in a debate; Westerners dig in their heels.
To counter that problem, programs like "Call Before You Dig" have been started.
"We just had to be gutsy and dig in and wait for the late bit of patient counter attack to put a seal on the game.
