Did their actions help win the war and assure their ability to travel back in time? Was history closed off from them to prevent the alteration of the war?
From page 407:
That was the cruelest irony of all, that they had undone the future out of a desire to help – Eileen’s giving Binnie aspirin to bring her fever down and tearing up the letter to keep the children from drowning. Mike’s unfouling the propeller because he couldn’t stand the thought of fourteen-year-old Jonathan being killed and pushing the two firemen away from the collapsing wall.
Even the act which had set it all in motion had come not from malice but from an innocent desire to see something beautiful. It seemed impossible that compassion and kindness should be the weapons of destruction, that just the opposite should be true. It was true that in a chaotic system, good actions could have bad consequences, but why--?
From page 398, when Mr. Dunworthy, the chargé d’affaires of the time-traveling group, tries to explain what might have happened:
Mr. Dunworthy shook his head. “We were wrong about the slippage’s function. It wasn’t a line of defense guarding against damage we might do to the continuum. It was a rearguard action against an attack that had already happened – an attempt to hold a castle whose walls had already been breached.”
“By time travel,” Polly said.
“By time travel. . . .”
How the teams work to get home – some eventually do -- has a lot to do more with the mystery of seeing travelers in spots unexpected and ways in which accidents can be repaired, over time, than anything else.