[Paleo Conservative]

Wasn't Mercury suborbital?

Yes that particular Mercury flight was suborbital, but it did test the reentry system and heat shields. We were in no way behind the Soviet Union in developing our space technology in 1961. It's just that the Soviets were willing to take greater risks with their personnel. The statement I quote said that our reentry systems were not perfected until several years later which is not true. Both Allan Sheppard and Gus Grissom successfully reentered the atmosphere in 1961, and the four manned orbital Mercury flights also successfully reentered the atmosphere.

[CharacterCounts]

Actually, I now remember it. One of the functions of the flight was to test the heat shields for the Gemini flights.

[Fred Hayek]

The Mercury-Redstone suborbital flights of Grissom and Sheppard used a different type of heat shield, in that case a heat sink. Heat sinks were also used on the RV's for the Atlas D and Thor missiles. The Mercury-Atlas capsules used an ablative heat shield. These were first tested in unmanned orbital flights.
Before the Vostok 1 (Gagarin's ride, I won't call it a mission since it was all ground control), the Soviets tested the Vostok craft with 5 Sputnik launches.