I have defeated the crabgrass with help from my husband and a small troupe of little boys. The neighbor kids from down the street that wander around together but without parents were drawn to our digging tools. The seven-year-old twins and four-year-old little brother joined our two year old and us in digging up the remaining crabgrass. I let them pet the new grass that we planted last week - they were very careful not to stomp it. They dug worms and put the mounds of crabgrass into the trash with us.
They took a short break on our porch swing with tiny bottles of water, the four of them fitting on the swing together, my very verbal two-year-old keeping up with the conversation about the bird poop on the rail. And then they went back to work.
One of them was drawn to my husband and watched while he raked up the thatch and remaining miscellaneous weeds - apparently my husband had paid the little guys with popsicles. Mostly, I think they liked the praise we lavished on them - they were very good helpers.
To put it in perspective, we filled four large paper lawn bags with crabgrass and thatch.
Later, after my son went down for a nap, the boys stayed with us - for hours. One of them helped spread the grass seed and spread fresh dirt over the top of it. I wondered if we should pay them or if we should be paid for babysitting all day.
It seems silly to me that I have such a sense of satisfaction from purging the weeds from my lawn, but it was an impossible task. There's nothing better than doing the impossible.