January 29, 1954:

 

Read this strip at gocomics.com.

Charlie Brown is still something more of a smart aleck than a whipping boy here, but it is an early example of Patty and Violet teaming up against the kid.  Later on he loses this ability to reflect feelings of inadequacy back upon assailants.

Look at Patty's satisfied arms-crossing in the first panel.  Man, that's some serious smug.  Also in the first panel, that's quite a lot of detail on the background there.

January 7, 1954: Anyone want to buy half a snowman?

Read this strip at gocomics.com.

Wow, that's a smug look on Charlie Brown's face in the third panel.  Whatever happened to annoy Patty, anyway?  The "inside" of the snowman is shaded for some reason, like it was filled with chocolate.  The carrot and buttons are missing, so it actually looks like Patty took slightly more than half of it.

Chagrimace!

September 27, 1952: "Well! If it isn't Charlie Brown!"

A funny strip. Lucy is certainly enjoying herself in this one!

February 19, 1951: Belittling remark

A rare piece of cartoon metaphor here, as Patty's words literally diminish Charlie Brown in stature. I think this is probably the only strip which does this. Schulz must have been dissatisfied with this solution, as later strips show embarrassment using cross-hatching to represent blushing.

Snoopy's smug look in the last panel is a winner. There are strips where Snoopy just sits there smiling, uncomprehending, like a real dog, and there are strips like this one where he has more of a personality. Not close to Snoopy's later brilliance, but still, a step along the way.