The 1992 Ruby Ridge incident in Idaho is iconic to anti-government groups. Separatist Randy Weaver refused to surrender on firearms charges to a massive federal force surrounding his remote cabin for 11 days. His wife and teenage son were killed in the shootout. (UPDATE: This video, published in 2014, contains a reference to what is believed to be the longest armed standoff in U.S. history. John Joe Gray barricaded himself at his home in Texas after he was arrested in 1999 for assaulting a state trooper during a traffic stop. Charges were dropped later that year.)
In 1993, in Waco, Texas, dozens from the Branch Davidian religious sect died when federal agents raided their compound looking for arms. The conflagration inspired Timothy McVeigh, who later bombed a federal building in Oklahoma City in 1995.
The Capitol invasion came five years after the 41-day occupation of the Malheur Wildlife Refuge in Oregon organized by the Bundys, a family of Nevada cattle ranchers legendary for their armed confrontations with federal authorities over public lands. Rancher Cliven Bundy viewed the Capitol riots as a “retreat” saying “100,000 should have spent the night in the halls. 100,000 should have protected them.” The FBI has warned that violent homegrown extremists are the biggest threat today, particularly racial supremacy groups.