On 4 April, South African General Jan Smuts was sent to Hungary. He carried the proposition that the Hungarian communist government under Kun abide by the conditions previously presented to Károlyi in the Vix note. Smuts' mission also represented official recognition of the Kun communist government by the Allied council.
The Hungarians retreated to Szolnok and from there across the Tisza River. They established two concentric defense lines extending from the Tisza River around Szolnok. Between 29 April and 1 May, the Romanian Army broke through these lines.