A hypothetical Franco-Spanish victory at Trafalgar would still have left other British formations to fight, including the Western Squadron, Channel Fleet, and ships raised from reserve. Togo's force at Tsushima represented almost all immediately available Japanese naval power. There was no comparable Japanese force waiting behind it if Russia broke through. The Russian expedition was also its country's last practical attempt to reverse the war at sea. In this assessment, sending it was a decision driven by national pride despite the hopeless odds.
Notable Point · 48:20-49:54
Why Tsushima and Trafalgar had different stakes
The Trafalgar comparison turns on the forces still available after a battle: Britain had other formations, while Japan had concentrated almost everything with Togo.