I did a little reading on Chuck and found that "During the World War II years, Jones worked closely with Theodor Geisel, better known as Dr. Seuss, to create the Private Snafu series of Army educational cartoons. Private Snafu comically educated soldiers on topics like spies and laziness in a more risque way than general audiences would have been used to at the time." (wikipedia of course)
Here's one such video... it's pretty good. You'll recognize music, voices, and comic elements that would later become a big part of the Loony Tunes style.