By using Cassini as an upstream solar wind monitor we were able to infer increases in the interplanetary dynamic pressure upstream of Jupiter as the spacecraft approached the planet. Observations are made of the effect that these pressure increases had upon both the fields and particles within the Jovian magnetosphere as measured by the Galileo orbiter, which had subsequently re-entered the magnetosphere on the dusk side. As the external pressure increased, so too did the total field magnitude at Galileo (in particular the B-z and B-phi components). In addition strongly leading field angles were observed subsequent to the onset of the compression and strongly lagging fields during re-expansion, this being consistent with the concept of external control of the angular velocity of the magnetospheric plasma due to conservation of angular momentum within the system. Heating of the plasma can be seen clearly as a pronounced increase in particle flux as measured by the EPD instrument aboard Galileo. Changes in plasma velocity as inferred from energetic particle anisotropies at Galileo appear to be well correlated with the behavior of the changing magnetic field angle. The overall behavior and response time of the system appears to be comparable to that predicted by recent theoretical modeling of the Jovian magnetosphere-ionosphere coupling system.