Why "Attack?"

The "A" in RA-5C (and RVAH) stands for "attack."  The provenance of this term is quite illuminating.

US naval strategy in the Thirties focussed on defeating enemy fleets of roughly comparable size.  Japan was a signatory to the Naval Treaties of the 1920's which gave them this parity.

How to do this?  BGEN Billy MItchelll, the dogmatic bombing advocate, conducted some post WW I bombing tests which, he said, proved the surface ship was fatally vulnerable to the bomber.  The Navy was not so sure.  Horizontal bombing was typically conducted at high altitudes to avoid anti aircraft fire.  Hitting a small target (in solid angle) from say, 25,000 was not so easy even when not under fire.  Especially when the target, having observed the bomb release, could easily manuever away from the impact point.  As it happened,  wartime experiences confirmed this.

Still, Naval Aviation  was faced with the problem of how to destroy enemy fleets.  Warships were inherently hard targets and what is more, moving! Two approaches were developed.  The first involved diving the aircraft from high altitude to a release point perhaps a thousand feet in the air.  The target was much larger in solid angle at this release point, and of course, there was no time for it to maneuver away.  Thus, "dive bombing" became a principal tactic of the Navy in WW II, with specific aircraft designed for it (e.g., SBD Dauntless).  Note in the image nearby the perforated dive flaps to allow near vertical diving attacks for maximum accuracy.  Also barely  visible is a "crutch" used to fling the bomb away from the aircraft and its propellor  arc.

A second tactic involved using of a weapon invented in the late 19th Century, the naval torpedo.  These weapons typically carried very large warheads, and by nature of their  employment likely to be highly damaging (large holes near the waterline),  to the extent that warship design began to include specific armoring features ("torpedo bulges") to defeat this weapon.  Again, a specific class of aircraft, such as the TBD Avenger, shown nearby) was developed carry out this approach.  Note that the torpedo could be carried internally.  

Post war, the need for a dedicated torpedo bomber became less crucial since the major enemy fleets rested under the oceans.  Combining the functions of dive bombing and torpedo delivery become the requirement for future Navy power projection aircraft, now to be called "attack" and designated with an "A."

Airframers, paricularly Douglas and Grumman, prepared a number of combined torpedo/dive bomber prototypes during the post war period.  Typically twin engined with internal bomb bays and perhaps a turret (or two!) they they tending to be too big and heavy for carrier operation.  Eventually these designs were simplified to a single engine, single pilot, external carriage approach and become the Navy's first Attack aircraft, the AD Skyraider , (A-1 in modern nomenclature).  See Tommy Thomason's superb Strike from the Sea for an excellent treatment of the full story.

See  No Slack in Heavy Attack for the story of "Heavy" Attack