What was the main reason for Russia’s defeat in the Crimean War?

The Russian Empire lagged behind Western countries in economy and industry. The reason for this was serfdom, which hindered the modernization of society. Western countries, unlike Russia, managed to make a leap in development and improve industry and production methods.

Russian troops were armed with more backward weapons.

Another reason is that Russia has remained isolated and without allies. At the same time, the alliance of England and France, which supported Turkey, came out against Russia.