Final answer:
The sniper's position on a rooftop was advantageous due to elevation and view, allowing for effective targeting. However, it was also dangerous as it made the sniper visible and isolated, with limited escape options.
Step-by-step explanation:
The sniper's position on the rooftop provided a strategic advantage as it gave a wide view of the battlefield, allowing for better targeting of enemies and defense. The elevation meant the sniper could shoot from a distance, potentially without being seen, much like how 'aces' in aircraft engaged in combat could influence a battle through skill and bravery in 'dogfights'. However, the position was also dangerous as it made the sniper an easy target for enemy marksmen, especially if they were keen-eyed like the sentinel described as having a gray eye. The sniper would be isolated, with limited escape routes, and in full view if spotted. This precarious situation reflects the nature of warfare where high ground is desirable but can quickly turn inhospitable, echoing the counsel from ancient strategies about occupying sunny spots but retreating if the enemy has taken them first.