• Snapshot of 'Arrow' season 5 title card from official trailer

Snapshot of 'Arrow' season 5 title card from official trailer (Photo : YouTube/ The CW)

When The CW announced that it was making a four-way crossover involving "The Flash," "Arrow," "Legends of Tomorrow" and "Supergirl," the network teased that it was going to be a massive event. Just as promised, all four DC Comics shows delivered and scored the network's highest viewership rating in six years.

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The crossover started with The Flash (Grant Gustin) watching an alien spacecraft crashing landing and later discovering that the Dominators are planning to invade the Earth. The Flash, with the help of Cisco a.k.a Vibe, travels to other Earths to ask help from Supergirl, Arrow and the Legends team. They train and soon enough fight off the Dominators one episode at a time.

According to Deadline, the Nov. 28 broadcast was The CW's most-watched Monday night in seven years, with 3.26 million viewers tuned in. It is also the network's highest-rated Monday night screening in over five years in the 18-49 demographic. For that week, The CW saw an increase of 20 percent in total viewers compared to the same week last year.

Individually, the shows also booked new milestones courtesy of the superhero crossover event. "The Flash" saw its most-watch episode in two years with 4.15 million viewers. Its crossover episode was also the highest-rated episode for "The Flash" Season 3.

"Arrow" also scored its most-watched and highest-rated episode. This record was previously held by the crossover episode from last year.

The CW newcomer "Supergirl" also benefitted from the crossover as it saw its most-watched episode for this season. It also became The CW's most-watch show on the Monday night 8-9pm time period in more than eight years.

"DC's Legends of Tomorrow," on the other hand, came out as the big winner of the crossover event. It recorded its most-watched episode ever with 3.39 million viewers peeled on the show. It also scored its highest rating ever in the 18-49 adult demographic.

The four-way crossover is definitely a big success for The CW as it managed to pay attention to all of the characters involved without making the story too confusing or unconnected.

Meanwhile, the crossover event led to another major happening in "The Flash" Season 3. Wally West has sought the help of Harrison Wells to train as a speedster despite Iris' disapproval. E! News reported that this cliffhanger from the crossover episode will be explored further and more in depth in the coming episodes.