The Provos, Amsterdam anarchists, became widely known for their protests against the monarchy: including smoke bombs on Princess Beatrix’s and Claus von Amsberg’s wedding day, 10 March 1966. The Provos devised various kinds of 'White Plans' such as the well known White Bicycle Plan. The Provos also spread 'white rumours' to encourage moral panic in the country. Preceding Princess Beatrix’s and Claus' wedding day, there was a warning that LSD would be distributed to the mounted police's horses. Oranjecomité Parel van de Jordaan, which sent the message, was one of Provo's umbrella organizations.