Technically, the research will enables the ⚔ Martian Rescue mission, and the mission will triggers this event.
Thus, the Martian must control a territory (and staying in game), and you must border at least one normal Beastmen territory (non-gate, non-main base) so that the mission can be created.
Martian will immediately offer peace and some diplomatic proposal (if a suitable proposal is available).
Accepting peace will immediate cease all Martian attacks, including all ⚔ Counter Martians Appearance missions.
Now that we are finally able to communicate with the Martians, we have been able to start diplomatic talks. They are now no longer interested in fighting.
(Video Report with a martian speaking)
Well done. Every soldier we can save for fighting the Beastmen is worth his weight in gold.
Couldn't they send us their experts? These Martian technologies are so complex that we could really use their assistance.
That was not their intention, they want to wait and see how our cooperation will work. And by the way, they are asking for our help. One of their race has been captured by the Beastmen and the Martians are not able to save him at this moment.
We will consider the situation and if it's possible, we'll send in our troops.