[@Wildman13]

small point.. if you just used the cannons to fire thin darts with the same thrust you could easily wound a capital ship. a cannon to fire a small house into space, or near space could send a dart (think telephone pole) into space and do really terrible things to the ships. while i thinks its a facinating concept i find it difficult to believe. Personally i would say your best bet would be to capture EOM orbital defense and use it against them. 

not trying to make your life harder i swear, just adhering to plausibility.