A Century of Chess: Efim Bogoljubow (1920-29)
Efim Bogoljubow was born in 1889 in what is now western Ukraine. Very few top players have had such an inconspicuous rise to stardom as he did. He was strong enough to secure an invitation to Mannheim in 1914 but was largely an unknown quantity. Interned there, he chose to spend the war in Germany and probably had one of the more pleasant experiences that anybody did in the period 1914-18, playing eight tournaments with the other internees and really honing his game. By the time international chess started up again, he was already one of its leading lights and had a dizzying run in 1920-21, finishing third at Gothenburg, second at Berlin, easily winning a short match over Aron Nimzowitsch, and nearly upsetting Akiba Rubinstein. The question with Bogoljubow was always a certain lack of steadiness. In tournaments with a mixed field there was no player more dangerous than Bogoljubow, as he fully demonstrated at Bad Pistyan 1922 and Carlsbad 1923 but in smaller tournaments of top masters only his tendency to overreach could work against him. He had only middling results at London, Vienna, Maehrisch-Ostrau, and New York. The chess boom in the Soviet Union lured Bogoljubow back at a time when almost everyone who could was fleeing. He became the ‘captain’ of Soviet chess for two years, dominating the 1924 USSR championship and then, in the result of his career, winning at Moscow 1925. There is some reason to be suspicious of this, though. It was greatly in the Soviet Union’s interest to have a native player win and Bogoljubow ended up posting a hard-to-credit score of 7/8 against the other Soviet players.
It was inevitable, though, that there would be a falling-out between Bogoljubow and the Soviet authorities. In 1926, he was permitted to leave and settled in Triberg, Germany, where he lived for most of the rest of his life. The Moscow result had elevated Bogoljubow from being merely a dangerous tournament player to a bona fide contender for the world championship and he mostly cemented that over the next years, winning at Bad Kissingen 1928 and winning two matches against Max Euwe for the somewhat nebulous title of FIDE champion. His reward for that was the opportunity to challenge Alekhine in 1929. Bogoljubow was a worthy challenger and the match was closer than it's usually remembered, with Alekhine not pulling away until well after the halfway point. 
Bogoljubow's Style
1.Forward. Bogoljubow is a model player for people who are hot-blooded, bumptious, elbows-out, interested in just getting the job done. My personal theory is that David Janowski, Efim Bogoljubow, Efim Geller, and Veselin Topolov are all the same player — living entirely for the attack and never retreating or resorting to positional play unless they absolutely can't help it. This constant aggression made Bogoljubow the terror of mixed-level tournaments, but there was no one in the world whom Bogoljubow wasn't capable of catching on the back foot.
2.Power Play. When we're talking about Bogoljubow we're basically always talking about the same qualities — a relentless hyper-aggression that never really lets it up. Neil McDonald calls this "power play," which is basically the initiative. Here are two games in which we can see how power play works out against the very best in the world — in both games, Alekhine is able to either beat off a first wave of attack or organize his own counter-attack, but Bogoljubow has the flexibility to stay ahead in tactical complications.
3.Mess. A tremendous amount of Bogoljubow's tournament success had to do with the evident joy he took from slopping around in messy positions. Many grandmasters — especially in this era — tended to be perfectionist and to believe that chess was fundamentally an aristocratic game. But not Bogoljubow. He is at his absolute best in chaotic positions where everything depends on tactical horse sense.
Sources: Hans Kmoch has a reminiscence of Bogoljubow here. Edward Winter has a piece on him here. Sergei Soloviev has a book on him.
