Mount Etna in Sicily is one of the world’s most active volcanoes. It’s been erupting on and off for millennia (literally, the Romans talked about it plenty).
During a 1983 eruption, engineers tried and failed to plant explosives in order to reroute the flow. Apparently, they dug tubes to place charges, but the lava heated those tubes so fast that they would’ve ignited the charges well before they were placed in their positions.
In 1991, they tried again and this time succeeded. But it took a few tries. First, bulldozers built big piles of earthen barriers, but the lava rolled right through them. Then, the U.S. Army dropped concrete blocks from helicopters, but the lava consumed them (amazingly, lava is more dense than concrete so it’s not a great option).
Finally, in 1992, a “heroic dump truck driver” leveled a path beside the flow, which was now in a much more dangerous “lava tube,” and engineers placed 7.7 tons of explosives beside it (using lessons from 1983, they knew right where to put them). Alternative channels were also dug to help guide it away from the nearest town.
The May 1992 massive explosion cratered the lava tube, and successfully diverted the majority of the flow away from town. Coincidentally (or not?), the eruption began to subside shortly thereafter, which is why most consider the operation at Edlfell to be more impressive (though no less heroic).