にあって

1. 1In or under a particular circumstance or period (often にあっては), which shapes what follows.Ex. 1
2. 2Being in a particular position or status, with what is expected or appropriate given that role.Ex. 2
3. 3Even in a particular situation (にあっても), introducing something that holds despite it.Ex. 3

A formal, written pattern used in essays, speeches, reports, and commentary. It highlights the situation, era, or role someone is in, often one seen as special or severe, such as wartime or a position of responsibility. Compared with において, which simply marks a setting, にあって emphasizes the nature of the circumstances and what they entail.

• 1.
  において / におけるN3「において」simply states a time, place, or field objectively; it is the written-style equivalent of 「で」 and works for ordinary occasions such as meetings, whereas 「にあって」stresses how special the situation or position is. For ordinary places and times, only 「において」can be used.
• 2.
  にあたってN2「にあたって」means 'on the occasion of facing an important event' (a speech, preparations) and can attach to a verb in dictionary form, while 「にあって」means 'being in a special situation or position' and attaches only to nouns. They are sometimes interchangeable, but the former stresses the moment of facing something and the latter being in the midst of it.
• 3.
  とあってN1「とあって」attaches to nouns, verbs, and adjectives, stresses a scene brought about by special circumstances, and cannot be followed by forms like 「べきだ」; 「にあって」attaches only to nouns, stresses being in the situation, and allows both consequence and contrast. When the connection is consequential and the description objective, the two are sometimes interchangeable.
• 4.
  にしてN1「にして」does not describe one's circumstances; it points out that something happens at a certain age or in an instant (with nuances like 'only at,' 'already at,' or 'in the blink of an eye'), or, in the pattern 「AにしてB」, that someone holds two identities at once. Both attach to nouns and are written-style, but they cannot be interchanged.
• 5.
  中N3「中」is a neutral suffix that combines with nouns to objectively indicate an entire range, an action in progress, or a period within a deadline; 「にあって」is written-style, stresses the specialness of one's situation or position, and leads into what follows. When expressing a position or role, 「にあって」cannot be replaced with 「中」.
• 6.
  にしたらN2「にしたら」attaches to nouns for people or organizations and means 'from that person's point of view,' in a neutral register; 「にあって」attaches to periods, environments, or positions and leans toward written style. When talking about someone's position, they are sometimes interchangeable, but the former stresses a subjective view and the latter the position one is in.

にあって stresses being in a special situation or role and what holds true there. By contrast, において/における neutrally marks a setting, にあたって means 'on the occasion of' undertaking something, and とあって presents circumstances as the reason for a notable result. Similarly, にして marks a stage or level ('only at' / 'even for'), 中 is a neutral suffix for a period or ongoing state (as in 戦時中) without the emphasis on special circumstances, and にしたら means 'from the viewpoint of' a person.