Cancellation of the epic choral-opera will cost the company more than £50,000 in box office income, plus thousands more in wages for front-of-house and production staff. More than 1,400 people who have booked tickets will have them transferred or refunded.
But, as a company spokesman said,"You can't perform The Trojans without the citizens of Troy."
The chorus voted unanimously for five strike actions throughout the season in protest at plans to make one third of them redundant when the Coliseum closes for refurbishment in June.
The choristers are offering audience members a free recital of Verdi's Requiem at St Paul's church, Covent Garden, on Tuesday night.
Ian McGarry, general secretary of the union Equity, said choristers regretted having to strike.
"They believe the financial challenges facing the ENO can be addressed without critically damaging the company's artistic integrity. But as the ENO has refused to lift the threat of redundancy, or to talk to them about their ideas for alternative methods for savings, they feel they have no choice but to strike. ENO's loyal audience will be the losers if cuts at the ENO rip out its artistic heart."
The company remained defiant in its need to cut jobs and revise contracts to save money. Its chairman, Martin Smith, said: "The planned industrial action will only worsen the company's financial situation, damaging the potential of box office income for the remainder of the season."
He said the ENO was about to start a 90-day consultation period with unions and staff.
Equity confirmed that it was meeting the company, but said this was the ENO's legal obligation. A spokesman said: "The meeting is not a consultation over our alternatives to redundancies. At every stage, we have asked them to withdraw the threat of redundancies, and they have said no."
