For the mathematicians.

[Rory B Esq BSc]

100 years ago WW1 started, it lasted 4 years.
In some sectors of the Western Front 1,000 artillery shells landed in every square meter.
Assuming an average caliber of 75mm and length of 250mm per shell how much of the 'red zone' would have enabled man to build a ladder to the moon had the iron been used for peaceful purposes instead?

A rather sobering thought!

[Atterton]

Nah, we should have used to make a giant cannon and travel to the Moon in a large projectile.

[Fairley B. Strange]

Actually 75mm was about the lower limit for field artillery, not anywhere near the average size.

http://postalheritage.org.uk/uploads/Q_030040.jpg
http://news.bbcimg.co.uk/media/images/72397000/jpg/_72397046_154419800_10_getty_munitionsworker.jpg
http://www.halinaking.co.uk/Location/Yorkshire/Frames/History/1914%20World%20War%20I/Images/Munitions%20Factory.jpg

That's a lot more iron to add to the pile, but I'd second Atterton re melting it all into a Trans-Lunar cannon instead.