Father's birthday was not celebrated / We didn't celebrate Father's birthday because of the war / on account of the war. He got a bottle of wine, a bottle of schnapps and a pack of smoking tobacco. The actual gift, a nightgown that Adi had made, isn't here yet, since we can't send anything right now, but it's supposed to come by courier next week. The meatless birthday menu consisted of an imitation beef broth / a fake beef broth.

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Note added at 46 mins (2023-07-20 02:43:37 GMT)
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kriegsbedingt | Wörterbuch Englisch-Deutsch - dict.cc
https://www.dict.cc › s=kriegsbedingt
Deutsch-Englisch-Übersetzung für "kriegsbedingt" ... because of the war {adv} · on account of the war · resulting from the war {adj}.

German term (edited): kriegsmäßig ausfallen

Father's birthday had been ..

A common enough way of putting it - without making a meal of it and in the UK at least, as in 'Christmas had been cancelled by or over the Pandemic, shortage of money, someone's death etc.'.

No refs. or example sentences possible as wiped out 'by or owing to tech problems.'

"Father's birthday turned out on a war footing (this year). He got a bottle of wine, a bottle of schnapps and a packet of hand-rolling tobacco. The actual present, a nightgown that Adi had made, is not here yet, as nothing can be sent now, but it should come by messenger next week. The meatless birthday menu consisted of a fake beef soup..." etc. etc.

The phase is a little idiomatic: krieg=guerra; mäßig=with moderation; mäßig ausfallen = to turn out moderately [or to be moderate]. Then, to make sense we will say 'turned moderate', perhaps better 'become moderate'; it makes sense 'was moderated' too.
ausfallen -https://www.dict.cc/?s=ausfallenhttps://www.dict.cc/?s=ausfa...
ausgefallen, offbeat {ungewöhnlich} - unusual {adj}, https://www.dict.cc/?s=ausgefallen
Vaters Geburtstag ist kriegsmäßig ausgefallen - Father's birthday become moderate because of the war
mäßig ausfallen - to turn out moderately [or to be moderate] - https://de.pons.com/übersetzung/deutsch-englisch/mäßig
to turn out moderately means to turn inexpansive, economic, cheap
inexpensive {adj} - kostengünstig - https://www.dict.cc/?s=Inexpensive
economic, economical {adj}, cheap - kostengünstig - https://www.dict.cc/?s=kostengünstig
mäßig - with moderation - the same link

German term (edited): Vaters Geburtstag ist kriegsmäßig ausgefallen.

This rephrasing conveys the message that father's birthday could not go ahead in the usual manner, owing to the war, in a natural idiom. It adds 'usual ... celebrations' for explicitation.

Simpler formulations would be:
- War put paid to celebrating father's birthday.
- War ruled out celebrating father's birthday.

His birthday (celebrations) fell victim to the war/became a casualty of war

Compare with this:
"In 1968 George Washington’s birthday became a casualty of the Uniform Monday Holiday Act, when an act of congress shifted the fixed dates of certain holidays to designated Mondays in order to give federal employees several three day weekends." https://hintsandechoes.wordpress.com/2013/02/22/to-honor-all...

"Dozens of minor celebrations fell victim to the weather." https://www.theguardian.com/environment/2004/jan/02/weather....