Gamblers in Monaco casino; boats in Monaco harbor

Monaco's main revenue comes from Monte Carlo's casino, covering its needs through gambling. The Treaty of 1918 states that if Monaco's Prince does not have an heir, the country will revert to France, subjecting citizens to French taxes and military service.

What was the principal source of revenue for Monte Carlo?

How did the income from Russian bank players affect the tiny country's needs?

What would happen if the ruling Prince of Monaco failed to produce an heir?

What did the Treaty of 1918 decree regarding Monaco?

What were the implications of reverting Monaco to France for its citizens?