It was on August, 21st, 1957 when Sergei Korolev launched the R7 rocket booster
on its first successful launch and flight from Baikonur.
The R7 rocket booster, known as "Semyorka" to the Russians, and as the SS-6 "Sapwood"
to NATO in the role of an ICBM.
The R7 rocket booster, with modifications, served as a successful satellite launcher, sending up the Sputniks,
Cosmos spacecraft, etc.; served as a manrated launcher, sending up Gagarin and other cosmonauts into orbit;
as well as serving as a rocket booster for deepsace probes like Luna, Venera and Mars.
Today, the R7 has evolved into the Soyuz launcher with which it bears a strong resemblence.

You can make a valid point claiming August, 21, 1957 was the actual start of the "Space Age".

Sadly, the R7 in its military/strategic role was also the world's first ICBM, able to deliver nuclear megadeath
thousands of miles away in a matter of minutes, without warning to its potential civilian victims.
Mutually Assured Destruction has not disappeared in the past half century.

Jacob.

"And when they shall say peace and safety then sudden destruction shall come upon them like a woman
stricken with birth pangs. And they shall not escape." APOSTLE PAUL