When the Xindi attack hit the Earth, the sudden appearance of the probe which attacked Earth drew immediate retaliation from the ships protecting the planet, and it led to millions of protests and political attacks aimed straight at Starfleet, which had very few ships guarding Earth and maintaining law and order within the Terran Solar system.
Mansfield led the charge, of course. He harshly and bluntly criticised the whole of United Earth for being dependent on a single ship despite the waves of saucers he and his company had sent out among the stars over the last couple of years, gathering knowledge and gaining ground in the space exploration business game like Enterprise had. But he criticised Starfleet for wasting so much time building the NX class fleet one ship at a time, instead of constructing, say 6 of them in one bulk order and mass producing the parts so they weren't finished within a shorter time span.
When Jonathan Archer brought back news of the Xindi, their location within the Delphic Expanse, Mansfield ensured that Enterprise didn't go unaccompanied on such a dangerous, and potentially fool-hardly mission alone. What if the Enterprise was destroyed, and nobody knew about it? Humanity's survival was at stake, and Mansfield was going to be damned before he allowed something like that to happen.
Starfleet, bulldozed by the brutal logic and the tragedy of so many people dying in a senseless attack, agreed and accepted. Three squadrons were going with the Enterprise. The first would be to help the Enterprise in strength and numbers alone, the second was to explore the Delphic Expanse and learn more about the Xindi and the races that lived there, and the third was to travel behind the NX-01 fleet a few days behind in case they needed help. Mansfield had given them standing orders that if they found any sign of Xindi technology, they were to send it straight back to Earth for analysis and study. They knew the Xindi had more powerful weapons and a propulsion technology that was beyond Starfleet at this moment. They could use it themselves to send the prizes through. Piracy meant nothing to Mansfield, business and survival did. And the saucers were powerful enough thanks to the Nausicaan and Klingon technology they'd plundered and reverse engineered in a short span of time.
Many of the saucer captains had one or two problems with Archer. The human race was at stake. They've had a wake-up call. The human race's future was more important than morality.
Over the year, Mansfield's orders were met. Captured Xindi warships and other vessels full of hardware and weaponry were sent via subspace vortices back to Earth. Mansfield's organisation and Starfleet studied the technologies closely; they found while the different subspecies of Xindi had essentially the same technology, it was fundamentally different in some areas, so both Starfleet and Mansfield were delighted with the new technologies that they now had access to. A planetary defence grid which was a hybrid of Klingon, Nausicaan, Earth, and Xindi technology was built and put in orbit above Earth. Mansfield also pushed for large numbers of people to be ferried to other planets, in case Enterprise failed.
But when they returned from the Expanse and destroyed the Xindi's weapon which nearly destroyed the planet, the reports from the saucers showed how hazardous that region of the galaxy was; thermobaric clouds which prevented anyone from leaving, regions of space where the laws of physics themselves were in retreat with spatial anomalies which collapsed warp fields, races driven to piracy, a crew of Vulcans driven insane by Trellium-D, which was natural material which insulated the ships from the anomalies, a virus which transformed anyone into a whole new species, a group of humans from the 19th century who'd been kidnapped and shipped to the Expanse to work as slaves and were still in the 19th century who had turned the tables on their oppressors….
The most chilling bit of news came when the crews were debriefed.
The Xindi had been manipulated by another race, a race of time-travelling dimensional beings who had been stopped from transforming ordinary space into an environment that suited them. Defeated, the beings travelled back in time and manipulated the Xindi into thinking in the future, humanity would destroy their new homeworld. Mansfield believed many things were possible, and while he wasn't entirely certain about the possibility of time travel, he wasn't going to dismiss it like so many others.
Besides, there was plenty of proof.
The bizarre quantum dating anomaly which had been taken from the start of the mission.
The more advanced technology of the Xindi.
Reports of the Xindi-Reptilians who had ventured into Earth's past to create a bioweapon.
And on and on it went, but the biggest proof came from the report where the ships were taken back in time to stop a Time War, in an alternative Second World War.
Mansfield's organisation was separate from Starfleet's, so he didn't classify the incident which slowly became forgotten. He focused instead on the construction of his saucer ships. Everyone on Earth had seen how well they had performed against the Xindi warships, and now Starfleet was asking for him to partner up with them to design whole fleets of ships for their own use. Starfleet was a prideful organisation. But they were not so prideful that they didn't see the logic in denying that the saucers were better designed and quickly built compared to the ships they had built themselves. While the Enterprise was still a beloved ship, many in Starfleet began to take note as the years passed of the vulnerabilities of their ships when the subspace vortex technology was developed after years of reverse-engineering work that the saucers were better prepared for the rigours of space travel and met the challenges of the universe better than those of their predecessors.
Ship designers stopped designing starships with two hull designs, focusing instead on using a single body that was more compact, manoeuvrable and practical than anything previously designed.
Mansfield had successfully shown that two hull design starships were impractical, and the age of the flying saucer had been ushered in.
Author's Note - And... so there it is, the end of the short story. The human race is saved by the Enterprise and the saucer fleets, one of the things that irked me so much about Enterprise entering the Expanse was how only one ship was sent and if anything happened to Enterprise, and the ship was nearly destroyed or disabled more than once, what then?