Alcmene went to bed with Zeus, thinking that her husband was home unexpectedly from the war. Remember, a god can appear in any guise he chooses. Amphitryon was away at war, and Zeus appeared to Alcmene disguised as Amphitryon. Hercules is conceived when Zeus tricks Alcmene into thinking that he is her husband, Amphitryon. Now, like many heroes, Hercules has a conception and a baby-hood that are fraught with difficulties or, at least, with unusual elements.
