[1] They have been recognised as pioneers of the British thrash metal scene, and have also been referred to as one of the country's so-called "big four", along with Sabbat, Xentrix and Acid Reign.

[6] The two musicians were working to forge an ultra-aggressive, speed metal sound that was becoming more popular in the days of early Slayer and Metallica.

The album was released in May of that year through the label Under One Flag,[9] and Onslaught toured for about two-and-a-half years in support of it, playing with bands such as Motörhead, Exciter, Girlschool, Kreator, Nuclear Assault, Agent Steel, the Crumbsuckers, Angel Dust, Exumer, Messiah, Sabbat and a then-still unknown Anthrax.

[15] Onslaught toured for over a year in support of In Search of Sanity, playing alongside Annihilator, Xentrix, Slammer, the Crumbsuckers, Horse (not to be confused with the metalcore band from California), Drunken State, Sabbat and Dead On.

[10] In early 1990, Steve Grimmett decided to leave the band due to internal reasons, and was replaced by Tony O'Hora.

[citation needed] In 2005, the band were reformed[16] by Steve Grice and were joined by Sy Keeler, Nige Rockett, and James Hinder.

[18] On 25 March 2011, Steve Grice decided to leave the band on the eve of a major European tour due to a massive difference in the way reality was viewed.

Michael Hourihan (Extreme Noise Terror, Desecration) replaced him for the tour and in November 2011 became a permanent member of the band.

[citation needed] Former Anthrax singer Neil Turbin joined the band for their Thrash Invasion tour of US and Canada, Brazil and Chile, North and South America in 2014 as Sy Keeler was unable to take part due to family problems.

[20] On 27 March 2018, guitarist Iain GT Davies and drummer Mic Hourihan parted ways with Onslaught, to focus on other bands and projects amongst other reasons.

"[23] On 29 April 2020, Onslaught announced that vocalist Sy Keeler had once again parted ways with the band, citing his reason as, "Due to the nature of the modern-day music industry, some things simply aren't sustainable year after year and Sy has now taken a different full-time career path.

"[24] A few days later, it was announced that Keeler was replaced by Dave Garnett, who had previously performed in Onslaught by filling in for him the House of Metal festival in Umeå, Sweden that past February.

[27] Guitarist Wayne Dorman confirmed in a post on Facebook in December 2021 that he had begun writing new material for the band's new album.