Final answer:
The evidence supporting Haldir's statement is the division among the races of Middle-earth in The Lord of the Rings, caused by different perspectives and interests and manipulated by the Dark Lord, resulting in weakened opposition.
Step-by-step explanation:
Haldir's statement, "Indeed in nothing is the power of the Dark Lord more clearly shown than in the estrangement that divides all those who still oppose him," is supported by evidence throughout the story of The Lord of the Rings. One piece of evidence is the division among the races of Middle-earth such as elves, dwarves, and men. The estrangement between these races is caused by their different perspectives and interests, as well as the manipulation and corruption of the Dark Lord. The consequence of these estrangements is that the opposing forces are weakened and find it harder to unite against the Dark Lord's power.