Sauron relying on Saruman

[Foolofatook]

At the Battle of Pellenor Fields Sauron unleashed less than 10% of his forces. Pellenor was a trial of the strength of Gondor. The fact that the Rohirrim saved Gondor for a while may have helped Frodo sneak in to Mordor by occupying Sauron's eye long enough. But Saruman, the Rohirrim, and Gondor would not even have had a chance against the full onslaught of Sauron. You also need to remember that Sauron was fighting on all sides (supposedly in the South and East dependant on the other two Istari?) There was so little effort on the part of Sauron the first time around that it makes Saruman's armies seem pale in contrast. Also the armies of Sauron didn't fall to the arrival of Rohan but to the arrival of Aragorn and the ships of Umbar. Rohan delayed the enevitable just long enough for Frodo to get into Mordor.