Currently we tolerate the enslavement of humans but contrary to popular narratives about the US Civil War, we haven't fought any wars specifically to end slavery of other humans. We have had successful "slave rebellions" (e.g. Haiti, which continues to pay the debt imposed by their former slave masters for "damages and economic losses" to this day) but anti-slavery sentiments among those not in the demographic directly suffering from slavery never went quite that far. The anti-colonialist coup in Portugal was fueled more by the military's resentment over the forever-war required to suppress the colonies than any sympathy for their cause of liberation. The US Civil War was a reaction to the attempted secession of its then-member states rather than specifically their stance on slavery.

It's plausible that we'd see acts we'd consider terrorism in the name of animal liberation (arguably some of the ALF's past actions fit into this category) much like we have seen with other liberation movements. But as this is a struggle entirely led by those not themselves in the group of the oppressed, the dynamics are different from most civil rights struggles. Arguably even the abolition of formal slavery in most countries had less to do with zealous support from non-slaves and more with economic factors making slavery less appealing. And even then the countries only got away with slavery in their own mainland while still happily continuing to benefit from overseas slavery, much like we now mostly hide animal suffering in farms, closed trucks and meat processing factories rather than back alleys and town squares.