This short was produced for the Canadian government. During WWII, war bonds were a critical part of financing the army. (This was true in the US as well.) The Canadian government asked the Disney studio for a cartoon to promote them, but only had a very small budget.
The Disney folks kept the cost down by using existing footage of "The Three Little Pigs." There were only two real new animation pieces added. First, the third house's construction changed from red bricks to bricks made of war bonds. Second, the big bad wolf is now wearing some Nazi attire. Other than that, it's the same. Two of the houses are huffed and puffed down, etc.
The most interesting thing about this animation is realizing how ubiquitous this sort of low-grade propaganda was during WWII, if you didn't live through it.