Changing Role of the Cavalry and Gettysburg
'The role of the cavalry at the beginning of the Civil War was very limited. Horsemen of both armies were initially limited to patrolling and scouting, guarding supply trains and railroads, and providing escorts to generals. They were only used in battle as shock troops, a tactic which dated back to the Romans. A favorite jibe from the infantry was: "Did you ever see a dead cavalryman?" The foot soldiers believed the cavalry to be "dandies on horseback" who never saw much fighting and always had the easy life... Of course, truth was very different from the romantic descriptions of newspapermen. Soldiering on horseback was a hard life with plenty of danger.
The cavalry's military role had dramatically changed by 1863 and the armies were making use of their horse soldiers in more combat situations. Cavalry divisions were utilized by commanders as advance scouts and as a mobile fighting force. These new strategies culminated in the largest cavalry battle of the war fought on June 9, 1863 at Brandy Station, Virginia. Brandy Station was the opening clash of the Gettysburg Campaign.
Union troopers of General John Buford's Division opened the Battle of Gettysburg against Confederate infantry of General Heth's Division on July 1st. The cavalrymen were limited by their numbers and the moderate range of the carbines they carried, but were able to deter the Confederate skirmishers for a few hours until Union infantry arrived. While the armies did battle around Gettysburg, cavalry units skirmished in Hunterstown, Pennsylvania, and on several roads east of town.
Stuart's men were thwarted at Gettysburg by determined Union cavalry regiments which were better armed and led by experienced officers who had learned some of their tactics from the foe. Cavalry not only opened the battle, but closed it in a fierce contest east of Gettysburg. In a decisive showdown on July 3rd, Union General David Gregg's Cavalry Division thwarted a drive on the Union right flank by General J.E.B. Stuart's Cavalry. The battle was fought dismounted until a last desperate charge to break through the Union positions was beaten back by General Custer's Michigan Brigade. From Gettysburg on, cavalry would never be the same.'
http://www.civilwar.com/overview/315-weapons/148532-cavalry-62478.html
I had little understanding that the cavalry opened and closed the battle of Gettysburg, or awareness of the difference it made. Going by the article, Gettysburg made a difference to the cavalry as well.
@Waterloo50 , you might find some of the answers you are looking for here.