Breakdown of Versteck dich, die Feinde sind am Angreifen!
sein
to be
du
you (informal singular)
am
on the / at the
der
who, which, that (relative pronoun; die, das)
Questions & Answers about Versteck dich, die Feinde sind am Angreifen!
Why is Angreifen capitalized?
Because it is being used as a noun here! The progressive structure (sein + am + infinitive) literally translates to "to be at the [doing of something]". Since am is a contraction of the preposition and article an dem, it must be followed by a noun. Therefore, the verb angreifen (to attack) becomes the neuter noun das Angreifen (the attacking) and must be capitalized.
Could I just say die Feinde greifen an instead of sind am Angreifen?
Yes, absolutely. Standard German doesn't have a strict continuous tense like English does. Die Feinde greifen an can mean both "the enemies attack" and "the enemies are attacking". The am structure is just a colloquial way to strongly emphasize that the action is happening right in this exact moment.
Is the am-Progressiv structure appropriate to use in formal writing?
Generally, no. While extremely common in spoken German and casual texting, the am-Progressiv is considered colloquial. If you were writing a formal report or a novel, you would use the standard present tense and perhaps add an adverb like gerade (currently / right now) to emphasize the ongoing nature of the attack: Die Feinde greifen gerade an.
Why is it Versteck dich rather than just Versteck?