More than 100 officers swooped on homes in Brighton and Hove in one of the biggest drugs busts in years.
Fifteen men and three women have been arrested so far and drugs including heroin and crack cocaine worth thousands of pounds have been seized.
Operation Illinois has been running all this week but a news blackout prevented media reports until today.
It comes just a few months after the city was labelled the drugs-death capital of England and Wales.
Fifty-one people died from drugs in the city in 2003, almost one a week.
Detective Chief Inspector Graham Bartlett, head of Brighton and Hove CID, said: "Illinois is smashing an illegal trade that blights so many lives in this city."
The Argus yesterday accompanied police on one raid and watched as officers, some from the force's Tactical Firearms Unit, smashed their way into a terraced house in Lennox Road, Hove.
A neighbour, up a ladder painting, watched in amazement as search teams piled into the premises. Rooms were strewn with rubbish and needles.
A woman and man inside looked shocked as police, some wearing protective masks, burst in.
The woman was later arrested and bags of suspected drugs were taken away for analysis.
Police have been trained to search in safety.
Drugs paraphernalia and some weapons have been seized.
At one address, police found a prohibited air weapon and, at another, a crossbow. Police struggled with one suspect and he had to be restrained.
Mr Bartlett said: "Some of the so-called homes were in disgusting states - all brought about by the misery of drugs.
"Officers have safety equipment to protect them from hazards."
Raids are continuing for the rest of this week and 40 homes will have been searched by the time Illinois ends.
Two people were in court yesterday pleading guilty to supplying drugs and a further six people were charged the same day.
The operation follows months of covert surveillance and intelligence-gathering but Mr Bartlett said Illinois' success was thanks first to information supplied by the public.
He said: "The aim was to arrest dealers, search drugs dens and to provide high-profile reassurance to the public that we are cracking down on this trade.
"Police Community Support Officers are visiting communities where the raids happened and telling them how their information has been acted upon.
"Information from the public is vital and we need to encourage people to tell us when they see drug dealing.
"I am delighted with the results so far but this is not the end.
"Illinois was the largest operation of its kind for some time and similar crackdowns are planned for the future.
"Deal in drugs in this city and, sooner or later, you will get a call from us."
Illinois was part-funded by the Drug and Alcohol Action Team, backed by Brighton and Hove City Council and the Home Office. Both have expressed concerns about the rate of drugs deaths in the city.
Last November, a report by the International Centre for Drug Policy showed Brighton and Hove ranked higher than London, Birmingham and Manchester for the rate of drugs deaths.
The city's stood at 25.3 per 1,000 population, down from previous years, and work is continuing to cut the numbers further through drug treatment programmes.
Centre director Professor Hamid Ghodse said: "We are impressed with the improvements in Brighton and Hove ... and even the smallest change means several lives are being saved."
Brighton and Hove police urged anyone with information about dealers to call 0845 6070999.
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