Final answer:
Alexander I of Russia's success against Napoleon's invasion was not due to proactive confrontation but his strategic use of defensive tactics, withdrawing and letting the harsh environment and long supply lines weaken the French forces. This approach, paired with Russia's winter, led to the depletion of Napoleon’s army.
Step-by-step explanation:
When considering What was Alexander's main successful trait in fighting Napoleon's invasion, we must clarify that Alexander the Great and Napoleon are figures from different historical timelines. Alexander the Great, known for his immense military achievements and conquests, lived centuries before Napoleon. However, if we are discussing Tsar Alexander I of Russia and his successful trait in countering Napoleon's invasion, the closest answer would be his ability to implement a brilliant military tactic. During the Napoleonic Wars, Alexander I employed a tactic of retreating and drawing the French army deeper into Russian territory where logistical lines became overstretched and troops were worn down. Combined with the harsh Russian winter, this strategy significantly weakened Napoleon's Grande Armée, facilitating its eventual defeat. Unlike Napoleon, who was known for his coordination of multiple army corps and brilliant use of military logistics, Alexander I's success was not grounded in individual heroism on the battlefield or preemptive attacks but rather in these comprehensive strategic defenses including scorched earth policies and guerrilla warfare which sapped the enemy's strength.