While the central themes of U2's previous albums Boy and October were adolescence and spirituality, respectively,[4] War focused on both the physical aspects of warfare, and the emotional after-effects.

War was a commercial success, knocking Michael Jackson's Thriller from the top of the UK charts to become U2's first number-one album there.

Following an argument with his girlfriend, and a period of doubt in his own song-writing abilities, the Edge – "feeling depressed... channeled [his] fear and frustration and self-loathing into a piece of music.

A local violinist, Steve Wickham, approached the Edge one morning at a bus stop and asked if U2 had any need for a violin on their next album.

A chance meeting with Andy Newmark (of Sly & the Family Stone) – a drummer who used a click track religiously – changed Mullen's mind.

Bassist Adam Clayton had already left the studio, and the three remaining band members decided they did not have a good song to end the album.

The song describes the horror felt by an observer of The Troubles in Northern Ireland, specifically Bloody Sunday.

Already a departure from the themes of innocence and spirituality displayed on the group's first two albums, "Sunday Bloody Sunday" introduces the album with a startling, military-esque drum beat by Larry Mullen, Jr., a fuming solo by the Edge that segues into staccato bursts reminiscent of machine gun fire, and pointed lyrical couplets such as: "And today the millions cry / We eat and drink while tomorrow they die."

In a favourable review in Rolling Stone, J. D. Considine said, "the album's musical strengths are largely the product of well-honed arrangements and carefully balanced dynamics".

He added, "the songs here stand up against anything on the Clash's London Calling in terms of sheer impact, and the fact that U2 can sweep the listener up in the same sort of enthusiastic romanticism that fuels the band's grand gestures is an impressive feat.

"[4] Critic Dave Marsh said that despite not "match[ing] the pure chilling intensity" of Boy and Lillywhite's production not giving the guitars enough prominence, War was a "solid set".

"[24] Robert Christgau of The Village Voice wrote that "the deadly European virus that's always tainted this band turns out to be their characteristic melodic device", adding, "The Edge becomes a tuneful guitarist by the simple expedient of not soloing, and if Bono has too many Gregorian moments his conviction still carries the music.

"[26] Dan Kennedy of the Orlando Sentinel said that on War the group "more clearly define its philosophical stance" and that below the sense of despair on the surface is a "voice of hope that flies in the face of most rock postures".

[28] In a review published in the Albuquerque Journal, Rick Shefchik said, "The arrangements on this precocious young band's third album are brighter than before", giving their politically motivated songs a "pop sound they once seemed to be avoiding".

[21] Bill Ashton of the Miami Herald called War one the year's best records and said it was the band's "most consistent album yet, full of plaintive lyrics and fiery guitar work" and a rhythm section that "sharpened noticeably" since October.

[22] Philip Smith of The New Zealand Herald commended the band's maturing sound and labeled the album "a classic".

The review concluded, "In trying to escape formula, U-2 too often loses the battle, but this willingness to try the new, added to its still-bracing basic thrust, indicates how distinctive the band is even in failure.

"[25] By contrast, Liam Mackey of Hot Press in the band's native Ireland said that War "totally eclipses" the group's first two albums and called it a "major leap forward, conceptually and technically".

He praised the "resourcefulness and imagination" of the Edge's guitar playing and said the album "offers watertight evidence of the band's standing as a genuinely original force in contemporary music".

[35] Over the course of the tour, the band began to play progressively larger venues, moving from clubs to halls to arenas.

[47] Both releases received extensive play on the radio and MTV, expanding the band's audience and showcasing their prowess as a live act.

"[63] Chicago Tribune critic Greg Kot deemed War a "breakthrough" for U2 in which "the band's passion comes through with gripping clarity.

"[55] Stephen Thomas Erlewine of AllMusic viewed it as U2's first album to achieve "greatness", finding that their lyrics – which he said "came across as grandstanding" in U2's earlier work – cohered into a "remarkably clear" vision on War and, complemented by the band's "muscular, forceful performances", succeed at "making the universal sound personal".

[51] J. D. Considine and Nathan Brackett's overview of U2's discography in the 2004 edition of The Rolling Stone Album Guide states that with War, the band brought more focus to their songwriting and effectively balanced personal and political subject matter, while also creating a musically "richer and more varied" album than October.

[59] Reviewing War upon its 2008 reissue, Blender's Jon Dolan opined that it marked a tonal shift from U2's more "inwardly focused" previous albums and demonstrated the band's newfound "titanic moral and sonic force",[54] while Rolling Stone's David Fricke commented that on War, "U2 sound like stars, not aspirants, ready for their money shot".

Club, said that the album showed Bono's mastery of "the art of the grand symbolic gesture" through "his inspirational iconography on anthems like 'Sunday Bloody Sunday' and 'New Year's Day'".

[53] Pitchfork reviewer Joe Tangari concluded, "The U2 we've known ever since had arrived on War, and even today it sounds vital.

[64] According to Treble writer Jeff Terich, War served as "a triumphant close to [U2's] post-punk trilogy" and "the dividing line between U2, the young Dublin new wave act and U2, the heroic stadium rock band".

[65] In a dissenting analysis, Bob Stanley believed the band had actually deviated from post-punk's regionalism and rejection of pop music universality by achieving progressively higher levels of international success.

"[66] All tracks are written by U2In 1993, Mobile Fidelity Sound Lab remastered the album from the original analog master tapes and released it on a 24kt gold plated CD.