Dates of note from the 1950s:

1951 - (date unreadable)
Snoopy's first thought balloon

November 14, 1951
Charlie Brown fails to kick the football for the first time, but Violet was the one holding the ball

September, 1952
Linus's first appearance

November 16, 1952
Lucy first holds a football for Charlie Brown

June 1, 1954
Debut of Linus' security blanket

July 1954
Pig-Pen is introduced

January 5, 1956
Snoopy first walks on two legs

1958
Yale University names Schulz Cartoonist of the Year.

August 23, 1959
Sally debuts (as an infant)

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