Cardiff - England needed to prove in the first Test they could compete with Australia and the hosts showed in Cardiff they are a "dangerous side" by winning with a day to spare, captain Alastair Cook said on Saturday.
Australia began the series as hot favourites to retain the Ashes they captured with a 5-0 rout in 2013-14 but were largely outplayed as England eased to a 169-run victory.
"It was really important for this group of players to show we can compete with Australia," Cook told a news conference.
"I remember sitting here before the Test match and everyone was talking about what happened in the previous series.
"I was getting a little bit frustrated because there is nothing we can do about that," said Cook.
"As a group of players, to come and start the series well was important because it showed we do the basics well and when we play with that kind of attitude we can put Australia under pressure."
England warmed up for the Ashes with two drawn series against West Indies and New Zealand, losing the last Test against both.
Cook, however, said his side had felt the "feelgood factor" since Joe Root and Ben Stokes rescued England with a stand of 164 against the Kiwis at Lord's.
"It started off with that partnership between Joe and Ben when we were 30-4 at Lord's against New Zealand and carried on from there in all forms," he said.
From the moment Root was dropped by Brad Haddin on the first morning of this Test when England were three down with 43 on the scoreboard, England did not look back.
Root, despite his team's precarious position, played carefree and stylishly to hit a superb 134 and a clear attacking intent also brought half-centuries for Stokes, Gary Ballance and Moeen Ali.
England amassed 430, dismissed Australia for 308 and again batted with intent to set the tourists a victory target of 412 that was never threatened.
"It's not going to work every time. I'm sure Australia will bounce back and put us under pressure at certain times but if we can go out there and show off our talent, guys go out and express themselves then we are a dangerous side," Cook said.
The second Test at Lord's starts on Thursday.