Simply put, Montero's plan was this.
First, form a large merchant convoy—or an envoy mission would work too.
Then, under the banner of friendly "visits," travel to the surrounding Black Hole Cavity Realms and, in the process, offer to help the civilizations within those realms strengthen themselves.
As for how to strengthen them?
Sell them all sorts of military equipment.
For example, the Black Hole Engines Montero mentioned, along with various other things.
If a Ninth Generation Black Hole Engine were placed before you, could you really refuse it?
Of course you couldn't.
That made things easy. I could sell you everything at bargain prices, since we were all good friends!
Then, once a century or more had passed and the Alliance was ready for its third round of outward expansion, the civilizations in those Black Hole Cavity Realms would have completed a full military refit.
At that point, the Alliance could practically go over and accept their surrender directly.
What? You refused to surrender?
Easy enough. Activate the backdoor. If I wanted your warships to self-destruct, they would self-destruct. If I wanted you paralyzed, then you had to be paralyzed.
What would you use to resist?
"Lin Fan, what do you think?"
Beside him, Lin Zhen turned to ask Lin Fan.
The other civilizations, Montero included, also looked over.
Everyone understood that the final decision would ultimately depend on this man's opinion.
"It's feasible. On one hand, we'd be planting mines for them; on the other, we'd use arms sales to drain away their war potential!"
"Of course, what Montero just mentioned were Black Hole Cavity Realms that had already been unified and possessed considerable strength. As for those that haven't been unified, or haven't been completely unified—"
"We can also support the weaker side and let them fight