I think this must be a night of high tension. Pippin has a go at the Palantir while he thinks everyone is sleeping and causes quite a stir. Everyone is roused and there is an urgency to get as far from Isengard as possible as fast as possible. Gandalf takes off with Pippin immediately. Aragorn, Theoden, and the rest of the company head for Helm's Deep not long after them. Poor Merry, feeling small and in the way and at a loss without the unfailing cheerfulness of Pippin is left to ride with Aragorn. You can feel how forlorn Merry is.

The company had not gone far when they are overtaken by riders coming upon them at high speed. All the company stops and prepares to fight. Even Merry, who is set on the ground by Aragorn so that he can be free to do battle as needed, draws his sword and prepares to do battle as best he can standing next to Theoden. I can imagine how small he must have felt, standing on the ground amongst all the stamping, restless horses. The sound of Halbarad's voice calling out for Aragorn son of Arathorn must have been as beautiful a sound as the song of the elves to Aragorn's ears.

Halbarad tells Aragorn that he came at Aragorn's summons and we learn that Aragorn sent no summons other than his heart felt wish in his thoughts that his fellow Dunedain were with him. Here, like a gift are 30, strong rangers. Among the Dunedain are the twin sons of Elrond, Elladan and Ellohir. Ellohir brings a cryptic message from his father:

"The days are short. If thou art in haste, remember the Paths of the Dead."
"Always my days have seemed to me to be too short to achieve my desire," answered Aragorn. "But great indeed will be my haste ere I take that road."

In addition to the message from Elrond, they bring a gift from the lady Arwen and they bring their strength in arms and in companionship. Tolkien makes it clear that Aragorn is overjoyed to see them. The company heads off to Helm's Deep and arrives at first light.

Many are able to take some rest but there is not rest for Aragorn who retreats with Halbarad to take council. In addition, he spends a little time with a certain Palantir wresting it, by pure force of will, from Sauron and claiming it as his own. What he learns from the Palantir tells him that he does indded have need of great haste. Gondor is at risk. Aragorn must move faster than Theoden can muster and leave Rohan. After consulting with Theoden and against his advice, Aragorn decides he must follow a separate path. Sending Merry with Theoden to the Muster at Harrowdale, and after a brief rest for food and further council, Aragorn takes his company and heads for The Paths of the Dead.