The Galactic (Old) Republic lasted for 25,034 years, and the last three years of it's existence (25,031 to 25,034 years after the original foundation of the Old Republic) saw it pitted against the breakaway Confederacy of Independent Systems in the so-called Clone Wars.
25,034 years after the foundation of the Old Republic saw the end of the Clone Wars, the extermination of the Jedi Order (Order 66), the formation of the Galactic Empire, and Supreme Chancellor Palpatine becomes Emperor Palpatine.
The Rebel Alliance (more properly called the Alliance to Restore the Republic) was founded when the Galactic Empire was 17 years old (25,051 years after the foundation of the Old Republic).
The Battle of Yavin, in which the original Death Star battlestation was destroyed, occurred when the Imperial regime was 19 years old (25,053 years after the foundation of the Old Republic).
The Battle of Hoth, where the Rebel Alliance headquarters was invaded by Imperial forces, and forced Rebel elements to evacuate the planet Hoth, occurred when the Empire was 22 years old (25,056 years after the foundation of the Old Republic).
The Battle of Endor, resulting in a severe Imperial defeat above and on the Forest Moon of the planet Endor, the deaths of Emperor Palpatine and Darth Vader, and the destruction of the second and last Death Star battlestation, occurred when the Galactic Empire was 23 years old (25,057 years after the foundation of the Old Republic). Soon after the Battle of Endor, the Rebel Alliance forms a new government called the New Republic, and the Empire splits into rival factions.