It was mandatory for all males to serve, after the age of 18, and not later than 28. There were exceptions (many) usually based on health issues, or on good connections. Ljubojevic, like many other well known young man, could have easily avoided the Army if he had wanted to.

He stayed in the Zagreb garrison, spending most of his time in Zagreb chess clubs, where I met him and even played a few Blitz games with him. Also, during that time he participated, and shared the first place, in the national championship of 1977which took place in Zagreb.

1976-77 was also a matter of good timing, with the idea to have plenty of time to prepare for the next WC cycle. Although Ljubo never qualified for the Candidates, he still remained amongst the top ten throughout most of the 1980s.

Regardless of some minor differences in accent and idioms, Croatian and Serbian are essentially the same language.

<..in 1979 he played in Sao Paulo the IT..> By "IT" are You referring to the Interzonal? I'm sure in 1979 Ljubojevic played in the Riga Itz, which was, perhaps the worst showing of his career.

First a game where Ljubo displays impeccable technique to defeat a future Fide Wch.

Ljubojevic vs Khalifman, 1993

This "little known" game was annotated by Timman in "power chess with pieces" and shows why Hubner characterized Ljubo as someone especially deadly in clean and neat positions.

However, the majority of people know him as a great tactician with a liking for strange set ups. In the following game he defeats one of the most solid GM's of the time by a TN pawn sac that for a moment seemed to refute the sicilian ;) A lot of tactical fireworks in a game that has been named the best of the 2nd half of the century.

Ljubojevic vs Ulf Andersson, 1976

And as an encore a very entertaining draw against a young player entering the world's elite.

My recollection of his hayday was the mid/late 1970s. I'm also surprised he wasn't in the Top 5 at least once or twice - he was indeed considered WCH material for a time. I'd make him high 2700s at his peak vis-a-vis today's ratings.

I honestly don't think he ever hit his full potential. He was known as a violent attacker, ala Tal, but to my mind there were more positional flavors into the mix of his style. Some very deep and creative things going on in many of his best games.

1975-1978, 10-12th
1979-1982, 15th-23rd
1983-1984, 3-4th (peak)
1985-1986, 10-15th
1987, 6th
1988, 15th
1989, 30-40th
Jan 1990, 10-11th
July 1990-Present, Out of top 30