In February, a builder in Plymouth was digging–something builders do a lot of–when his shovel hit a piece of rusty metal. That doesn’t sound like national news, but after a bit of exploration he recognized the size and shape of an unexploded bomb and hit the panic button. As did the experts once they were called in. 

What he’d found turned out to be a 500-kilo bomb left from World War II. (If you want that in pounds, multiply it by 2.2 and eat three squares of dark chocolate, preferably before breakfast.) Some 1,200 people were evacuated from the area and over 100 military personnel were brought in as a kind of unintentional trade. 

Or in a different article, over 10,000 people were evacuated, but let’s not worry about it. I suspect we’re looking at two different categories–the residents who had to move immediately; the ones who had to move later to clear the route the bomb took to its final exploding place; the ones who ran screaming from their houses even though they weren’t anywhere close. Or else we’re looking at a roving zero, which plonked itself down in somebody’s text. I love to see numbers mess with people other than me. I take up enough of their attention, so it’s only fair that I step back sometimes. Anyway, let’s just say a lot of people had to move out of their homes. Roads were closed. Trains and buses were stopped. Reporters and photographers gathered. Ink was spilled.  

Irrelevant and ever so slightly ironic photo: a sunrise, looking as hopeful as any sunrise will

It took days to dig the bomb out, and once that was done (without setting it off, mind you) they still had to move it through the city and out to sea, where they could detonate it safely. Or at least safely if you’re not a marine creature minding your own business in an area humans consider uninhabited. But let’s not think about that. Let’s just call this a happy ending. The alternative–or at least one alternative–was blowing the bomb up where it was, destroying homes for blocks around and threatening water and gas lines.

What’s an unexploded bomb doing in Plymouth?

Plymouth–like London; like a lot of British cities–was bombed heavily during World War II. It had a major naval dockyard and a large military presence, making it an important target. 

Not that a city needed strategic value to be bombed. Leftover bombs were dropped pretty much anywhere at the end of bombing raids so the if the planes carrying them were being chased they could gain height and speed and get the hell out of there. And non-strategic cities were bombed on the theory that destroying historic sites would damage morale, which is why Exeter was bombed. The target was the Cathedral, which they missed, but they wrecked a lot of the city center. When the city rebuilt, it left some of the wreckage in place as  monuments to–well, you can read the monuments any way you like: to those lost in the bombing, to everyone who died in the war, to everything that was lost. Maybe it’s the openness that makes the remains so moving. 

But back to Plymouth, with its value as a strategic target. Want to do numbers? Of course you do. Numbers make us all sound like we know something. 

During the seven worst days of the Blitz, the city was hit with 6,000 general purpose bombs (hands up anyone who knew there was such a thing as a general purpose bomb) and 105,000 incendiary bombs. In four years of bombing, over a thousand civilians died and over three thousand were injured, That’s out of a population a bit north of 200,000. More than four thousand properties were destroyed and eighteen thousand were damaged. The city center was pretty well flattened. It was rebuilt in the late forties and fifties and (unsolicited opinion follows) is pretty grim. 

Never mind. Those weren’t easy times and it’s easy to criticize when you don’t have to wrestle with the problems that must’ve been involved. 

To take in the scale of what Plymouth was  living with during the Blitz, though, you have to think about not just the 59 bombing raids but the 602 alerts, when people would  haul themselves out of bed and hide someplace they hoped was safe but knew to be, at best, only safer than staying put and pulling the covers over their heads.

In the midst of all that bomb-dropping, some 10% of the bombs dropped didn’t explode.

How many unexploded bombs is the UK sitting on?

It’s hard to get an exact count. You can call for them to put their hands up all you want, but they won’t do it. Something like 45,000 have been found, although that’s probably an underestimate. The Ministry of Defense deals with some of them, but others are dealt with by private companies, and there’s no central count for us to tap into.

If we can’t get a count of the bombs that have been found, we’re even further from getting a count of the ones sitting under someone’s garden, minding their own lethal business. The closest I could come to a number is that some 500,000 “items  . .  of unexploded ordnance” are in the waters around Britain, mostly from World Wars I and II, although some are from exercise drills and other fun stuff. 

Are they dangerous? Um, yes, at least potentially. Some are known and marked on maps. Others aren’t. 

Ooooh, don’t go wading. I think I see something just under the sand.

On land, though? The BBC says there are “potentially thousands.” We’ll go with that. It’s vague enough to be unchallengeable. And they’re at least as much of a threat as the ones underwater.

“What makes unexploded bombs dangerous is their unpredictability,” one expert said. Over time, they might have degraded. Or they might’ve become more dangerous. We’d be wise not to gamble that eight or so decades of sitting in the ground, contemplating the horrors of war, has made pacifists of them.

How did Britain deal with them during the war? 

At the beginning, badly. Bomb disposal officers could expect to live two months. They were issued a hammer, a chisel, a ball of string, and if they were lucky, a stethoscope. 

What was the string for? Your guess is as good as mine, but the stethoscope was for the bomb, not to see if their hearts were still beating.

“The running joke was ‘join the Army and see the world, join the bomb disposal squad and see the next world’,” historian Steve Day said.

(You’ll find that in the BBC link that’s just above if you want to make sure I didn’t invent it. I remember just enough about footnotes to get twitchy when I don’t put a link in for quotes.)

With time, they–those who lived and the folks in charge–got better at it. The key was understanding the fuses. One, Type 17, had a clock that could be set to go off anywhere from a minute to a few days after the bomb landed, but it could be gummed up with either a sugar-based fluid or a magnet. When the Luftwaffe upped its game and introduced an anti-tamper fuse, disposal experts learned to drill into the side of the casing, force steam in, and let the liquid TNT drain out. 

These days they use pretty much the same techniques, but robots get to do the most dangerous work.