[Old Teufel Hunden]

"When there are fat, guaranteed government contracts to be had, manufacturers move very quickly."

Cannon's were made of iron back then. There's a reason that Pittsburgh became the iron and steel capital. It has a unique set of qualities (coal, water, natural resources) that made it this way. In 1863, it would have taken years to re-build the foundries and mills necessary to make these cannons. No matter what guaranteed big fat contracts said. That was a simplistic answer born of lack of understanding.

[wideawake]

That was a simplistic answer born of lack of understanding.

Not really. Destroying mills and foundries is a setback.

But taking Pittsburgh would not have meant an end to the Union's supplies of iron ore, or coking coal or water.

There were large foundries in Massachusetts, not as well-located as Pittsburgh, but still productive.

Pittsburgh's greatest advantage was Rodman's patented process which gave it a technological edge. That edge was transferable in an emergency.

I'm not sure how well you understand Pittsburgh's role in all this - it was not a magical place. It had great advantages which made it a very economical area to forge iron and therefore a place that attracted engineering talent.