Tens of thousands of protesting farmers have marched, rode horses and drove long lines of tractors into India’s capital, breaking through police barricades to storm the historic Red Fort.

It was a deeply symbolic act that revealed the scale of their challenge to Prime Minister Narendra Modi’s government. They waved farm union and religious flags from the ramparts of the 17th century fort, where prime ministers hoist the national flag on the country’s August independence day holiday.

Riot police fired tear gas and water cannons and set up barricades in an attempt to hold back the protesters Tuesday, which was Republic Day, celebrating the adoption anniversary of the Indian Constitution. The farmers have been demanding the withdrawal of new laws that they say will favor large corporate farms and devastate the earnings of smaller scale farmers.