The last US horse mounted charge into a full scale battle with modern weaponry against opponents with tanks was not very long ago indeed. October 2001 saw an Afghan mounted force charge a much larger Taliban force dug in and armed with tanks and artillery, accompanied by 6 US Army Special forces. The Afghani losses were heavy but they completely demoralized the Taliban who surrendered in droves. A few US B-52's 'helped' by providing close air support, only missing the Taliban by a few miles.
I doubt there will ever be a 'last' charge.
p.s.- not more than a few days ago, a US Armed and mounted unit charged a group of people invading the USA and captured many as they fled from the horses.