Removing an old subfloor in a 1940's home?

I am in the process of renovating a 1940's duplex. The sub-floor in the bathroom has some rot. The problem being there are multiple layers of flooring. I am down to the original 40's flooring and want to remove all of it to get a good look at the sub-floor. The rot is easy to get out but the rest is proving a bit challenging. Over the sub-floor there is tongue and groove and after several hours I have about 1/4 of it out. Any suggestion on getting it up besides brute force? I was thinking of taking a circular saw and scoring though all the tongue and grove. Suggestions?????