Cavalry Captain Correa had a phone call with Colonel Lima of the 1st Armored Infantry. He still thought it'd be dead ahead of them, the first line of defense against the GUEs, but Lima clarified they had moved to Volta Redonda to quell labor unrest.
From Médici's perspective this didn't matter as he needed the psychological barrier. For Lima it might seem overkill to employ an entire battalion for that, but he didn't know the scale of the threat (the unionists did ponder on acts such as detonating rail lines, which would have even military value) and it was a particularly sensitive city.
Volta Redonda houses Latin America's largest steel works, a vital pillar in the national security strategy. Its management was strongly tied to the military. Once unionists prepared to strike, it activated its contingency. The military-technocratic response was proactive and finely coordinated whereas the strike was reactive and dysfunctional. Management rapidly cut off communications and arrested the ringleaders. Work was only partially paralyzed. The 1st Armored Infantry shut down a radio after 06:30, dispersed pickets at the factory entrance at 07:00 and after 17:15 invaded the union headquarters.

This battalion had an indirect impact on the Minas Gerais front as it stood upstream of that other battleground, with a clear route. The 2nd Tank Battalion was also nearby, between the two theaters - since 1962 it was not in Rio de Janeiro but in Valença. Hence the Tiradentes Detachment, lacking any information and not knowing the 1st Armored Infantry was on their side (the books are completely silent on the 2nd Tank Battalion) sent a battalion of police and an antitank company to guard their flank against a possible attack from this side.