It is already clear that all effective opposition has collapsed. The 32-year-old leader, at first ridiculed as a romantic young adventurer, has won his 25-month struggle against the dictator, General Fulgencio Battista. Castro's army reached Camp Columbia, Battista's stronghold and army headquarters, this afternoon and met no opposition. Bands of his young followers, armed only with pistols, rifles and shotguns, have taken over all the main hotels in the past two days.