A few years back, my state (Wisconsin) has under attack by ALF and ELF. Among the mink releases and other sorts of harassment, vandalism and outright criminality, they firebombed a grain mill, one that processed grains for farmers in the area, including a mink farm. Do you think that burning this grain mill to the ground (and injuring firefighters) enhanced sympathy for ALF and ELF in this area? I can tell you that it was quite the opposite--and that extended to other environmental groups that aren't associated with them.
About 30 years ago, a group of four men used a truck bomb to bomb the Army Math Research Center on the UW-Madison campus. The bomb killed a father of infant twins who was working in the building. They did this--and flew over an ordnance center where one of my relatives worked and fake bombed the place (they used sacks of flour) to show the Powers That Be how easy it was--as part of their anti-war "statement." Do you think this helped the anti-war movement? Quite the opposite. Even those who were sympathetic--and Madison is quite sympathetic to any anti-war movement--to the anti-war movement was appalled and repelled by their actions. Only the most extreme supported these criminals (BTW, three of the four were caught and sent to prison for long sentences; one, Leo Burt, is still on the loose).
So did ALF and the four men who bombed the Army Math Research Center have an effect on history? I'll let you be the judge.