Now, I'm a handy person and my great temptation here was to head to Lowes grab a bag of Quickrete, fill in the damage and parge over the rest. Cosmetic fix. And I had almost talked myself into it. After all it would be much cheaper and I really can't be affording major repairs right now.
But a cosmetic fix would crack again in a few years, the wall would still be hollow and, really, the right thing to do is to rebuild it, with rebar reinforcements and concrete fill and mortar between all the joints -- the works, done right and up to code.
And these are the during.