This is one of my favorite Peanuts strips of all time. I actually didn't know that it showed up so early in Peanuts' run; I thought it was an early 60s strip.
Lucy is rapidly developing into her full horrific powers. She just smashed up Schroeder's bust with a <i>baseball bat</i> in his <i>own house</i>. And yet, Schroeder was fully prepared for it. Wow. And Lucy still hasn't really had many strips in which she's been infatuated with Schroeder -- in fact, I think this strip does a lot to solidify that crush as strip "canon."
It's interesting to note the contrast between Lucy's anger, violence and triumph to Schroeder's plain-faced endurance. The kid doesn't break expression the whole strip, except in panel 8, which is quite a weird look for the kid indeed. It's not quite anger and it's not quite sadness. There is almost something <i>pacifistic</i> about the way Schroeder handles Lucy here. It's really something.
Oh, and the strip is hilarious too.