In pictures: D-Day inventions

More than 700 gliders were used on D-Day, six of which took the first British troops into action.

Like most of the gliders, as the picture shows, they crash landed.

But they were supposed to - apart from natural obstacles and buildings, the Allies knew the Germans had used wooden stakes in fields to counter airborne landings.

So the gliders were designed with wings that easily broke off, plus the tail section could be blown clear by troops inside so they could get into action fast.