Tunneled bombs were used in a major way in WWI too.<p><pre><code>    In January, 1917, General Sir Herbert Plumer, gave orders
    for 20 mines to be placed under German lines at Messines. 
    Over the next five months more than 8,000 metres of 
    tunnel were dug and 600 tons of explosive were placed in 
    position. Simultaneous explosion of the mines took place 
    at 3.10 on 7th June. The blast killed an estimated 10,000 
    soldiers and was so loud it was heard in London.
</code></pre>
<a href="http:&#x2F;&#x2F;spartacus-educational.com&#x2F;FWWtunnelling.htm" rel="nofollow">http:&#x2F;&#x2F;spartacus-educational.com&#x2F;FWWtunnelling.htm</a><p>The craters are still there and form ponds in the fields where the battle took place.