Many of the BEST war movies were made during the pre-CGI era (read: practical sets and effects and sometimes hundreds if not thousands of real extras). Here are some of the best ones, all of which have a large war component (copy-pasted from an earlier comment):

Lawrence of Arabia (1962)

War and Peace (1966-67 quadrilogy)

Waterloo (1970)

Come and See (1985)

Tora Tora Tora (1970)

Kelly's Heroes (1970)

The Great Escape (1963)

Battle of the Bulge (1965)

Patton (1970)

Cross of Iron (1977)

Stalingrad (1993)

The Longest Day (1962)

A Bridge Too Far (1977)

The Bridge at Remagen (1969)

Heaven's Gate (1980) - Technically it's about a conflict which literally has "Wars" in the title

Spartacus (1960)

Lion of the Desert (1981)

All Quiet on the Western Front (1930 and 1979 adaptations)

El Cid (1961)

Spartacus (1960)

Ben Hur (1959)

The Fall of the Roman Empire (1964)

Cleopatra (1963)

The Ten Commandments (1956)

Quo Vadis (1951)

Potop/The Deluge (1974)

Mihai Viteazul/Michael the Brave (1972 duology)

Khan Asparuh (1981 trilogy)

Dacii (1967)

Columna (1968)

Gallipoli (1981)

Chunuk Bair (1992)

The Lighthorsemen (1987)

Battle of Neretva (1969)

Liberation (1970 film series)

Battle of Moscow (1985 film series)

Dr. Zhivago (1965)

Bridge on the River Kwai (1957)

The Dam-Busters (1955)

Dunkirk (1958)

Dacii (1967)

Columna (1968)

The Thin Red Line (1998)

Saving Private Ryan (1998)

Napoleon (1927)

Napoleon (1955)

Austerlitz (1960)

Das Boot (1981)

Glory (1989)

Gettysburg (1993)

Note: Most of the films on this list are free of the gore present in more recent movies since Spielberg's Saving Private Ryan (which kind of revolutionarised this aspect of war movies). But they do offer a sense of the epic spectacle and sheer scale which a lot of newer movies lack.