The high-intensity warfare in Ukraine represents the largest military conflict in terms of forces involved, casualties, and duration since the 1980-1988 Iran-Iraq war. But it is only the scale of the fighting that warrants comparison. Politically, the current events are unique in recent history.
The Iran-Iraq war was a clash of two regional powers, caused by differences between them. The military operations launched by the US-led coalitions against Iraq in 1991 and 2003 were about the world leader attacking an enfeebled regional power. What’s more, Iraq was totally isolated for ten years by 2003 and unable to buy or maintain sophisticated weapon systems. The Falkland war in 1982 and the Georgian-South Ossetian conflict in 2008 involved highly unequal adversaries, which made these engagements so brief.
The conflict in Ukraine is the result of differences between two great powers, the United States and Russia.
Therefore, the nearest historical precedent for the Ukraine conflict is the Korean War that ended almost seventy years ago. It was vastly different in terms of tactics and military equipment but rather close to the current developments in its political aspects. In both cases, a great nuclear power had to commit its forces in a protracted military campaign against a non-nuclear regional state that gets military support and military equipment from a hostile nuclear power.
In both cases, the conflict is about the future of the world order, not the fate of the country hosting the theatre of operations.