What was the primary reason the squatters petitioned the vice-president?

The primary reason the squatters petitioned the vice-president was that Maxwell had no legal right to the land. During this historical period, issues regarding land claims were prevalent, especially involving squatters who settled on land without formal titles or ownership. The squatters believed they had established rights to the land they occupied, but they contended that Maxwell's claims were not legally valid. This petitioning was a way for them to seek recognition of their situation and assert their rights in the face of legal uncertainties surrounding land ownership.

The other choices do provide context about the situation, but they do not capture the fundamental legal issue that drove the squatters to take this action. For instance, while it is true that they had established cattle ranches on the land, this detail underscores their investment in the land rather than the legality of their claims. Similarly, the notion that they paid for their portion of land might suggest ownership, but it was the legal disputes over claims versus actual occupation that primarily motivated the petition to the vice-president.