The backwater state of Espírito Santo had a single army formation, the 3rd Caçadores battalion in Vila Velha, directly under the Ist Army in Rio de Janeiro, and it did not take part in any operation. The governor had a neutral stance and allies in both the left and right, allowing him to survive in the new regime though he later fell to a political crisis. The local political atmosphere was parochial, distant from the radicalization in the core.
This state was irrelevant to Goulart's overthrow, but it leads to a controversial topic, that of American intervention.
The state's history and location >>36154 at once determined its irrelevancy and relevancy. The relevancy lies in being an alternative outlet to the sea for landlocked Minas Gerais, and thus a potential flashpoint if it entered a war with the primary sea route (Rio de Janeiro). This had already been the case in 1930, when it was invaded from Minas Gerais, and was even more now that there was a railway leading to the port in Vitória. A few months before March the governors of MG and ES had settled that in the event of a war troops would gather in Governador Valadares and supplies would be sent, allowing the coastal state to defend itself if it joined the rebel side. None of this happened. There was a police battalion in Governador Valadares but it moved to Juiz de Fora to join the column heading to Rio de Janeiro.

Darcy Ribeiro makes two claims, that the United States Navy was, in the 31 March- 1 April period, already in 12-50 nautical miles off Vitória, and that this included a land contingent which would land in the port and open a connection to Minas Gerais. Those are bold claims. As documents have been made public a clear picture of American intervention can be made.
https://nsarchive2.gwu.edu//NSAEBB/NSAEBB118/index.htm has the most relevant pieces of evidence.
https://history.state.gov/historicaldocuments/frus1964-68v31/d198 is of particular interest. Quoting it with the corrections made on the same day:
>Washington, March 31, 1964, 2:29 p.m.
>1301. For your personal information only, the following decisions have been taken in order be in a position to render assistance at appropriate time to anti-Goulart forces if it is decided this should be done.
>1. Dispatch of US Navy tankers bearing POL from Aruba, first tanker expected off Santos April 13; following three tankers at one day intervals.2
>2. Immediate dispatch of naval task force for overt exercises off Brazil. Force to consist of aircraft carrier and two guided missile destroyers (expected arrive in area by April 10), four destroyers, task force tankers (all expected arrive about four days later).
>3. Assemble shipment of about 110 tons ammunition, other light equipment including CS agent for mob control for air lift to São Paulo (Campinas). Lift would be made within 24 to 36 hours upon issuance final orders and would involve 6 cargo planes, 6 tankers, and 6 fighters.
>Unloading of POL by US Navy tankers (item 1) and dispatch of airlift (item 3) would require further development politico-military situation to point where some group having reasonable claim to legitimacy could formally request recognition and aid from us and if possible from other American Republics. Dispatch of tankers from Aruba and of naval task force does not immediately involve us in Brazilian situation and is regarded by us as normal naval exercise.