Some better quality images I was able to find:
to defend against the republicans
You mean the Nationalists. The anarchists were on the Republican side.
Those are some cool looking designs. I especially love the second pic. The holes at the front make it look very intimidating as if it has eyes that are watching the enemy.
Radical anarchist groups skirmished against communists and liberal republicans for like a week in Barcelona, known as the May Days, but that didn't really compare to the conflict against the Nationalists.
Not trying to make a dig at you at all, but I find it frustrating that the Spanish Civil War has been so heavily characterised by small incidents of leftist infighting, when really it was probably the single greatest example of diverse leftist unity behind a single cause in history. I think it's come from an attempt by western leftists like Orwell to discredit Stalin, and it's just stuck in the popular understanding of the conflict.
Not trying to make a dig at you at all
No worries, didn't perceive it as such! Thanks for the insight
So what you're saying is...
Anarchists are the original tankies