Final answer:
The type of constitution established in Athens in 404 B.C. was Oligarchy - a form of government where power is concentrated in the hands of a few. The oligarchy, known as the Thirty Tyrants, ruled for about eight months before being overthrown and democracy restored in Athens.
Step-by-step explanation:
The type of constitution established in Athens in 404 B.C. was Oligarchy. After the defeat in the Peloponnesian War, Athens was ruled by a small group of individuals who seized power. This form of government was known as an oligarchy, where power was concentrated in the hands of a few. The oligarchy in Athens after 404 B.C. was called the Thirty Tyrants.
The rule of the Thirty Tyrants lasted for about eight months before it was overthrown and democracy was restored in Athens. During this period, the oligarchy implemented harsh measures and purged perceived enemies from the city. However, their rule was met with resistance from the Athenian people, leading to their downfall.