Fifty G.91 R/4 aircraft were taken up from a cancelled Greek/Turkish order but were deemed to be unsuitable for operational use. Alternatively, these were used as training aircraft and were operated solely by "Waffenschule 50". When the initial training programme was completed, all R/4 aircraft were retired in 1966 and 40 surviving airframes were sold to Portugal. Other R/4 aircraft remained in Germany and were transferred to ground instructional use or for static displays at recruitment presentations. It has been claimed that the "Luftwaffe" had intended to equip a further four wings with the G.91R/3; however, initial operating experience with the type had allegedly left the Luftwaffe disappointed with the aircraft's performance and thus the intended further orders for the type were cut. A number of Luftwaffe G.91s were emblazoned with a "pig" emblem, this has been interpreted as a comment on the aircraft's lacklustre performance. On 1 January 1970, the "Luftwaffe" fleet consisted of 310 G.91 R/3 and 40 G.91T aircraft; by 1976, only 20 of the G.91 R/3 aircraft had been lost to accidents, a loss rate of 6 per cent. During the early 1980s, the G.91 R/3 was replaced in German service by the Dassault/Dornier Alpha Jet which operated in the same role; the last G.91 aircraft were officially retired in 1982. From 1961, Portugal became involved in fighting against nationalist movements in its African overseas territories, the series of conflicts becoming known as the Portuguese Colonial War. Portugal had deployed a detachment of F-86 Sabres to Portuguese Guinea in August 1961, prior to the outbreak of major fighting, but was forced to withdraw the jet fighters back to Europe owing to pressure from the United States and the United Nations, who imposed an arms embargo. This left a gap in air cover for Portugal's African colonies, both in the close air support role, and in the air defence role. In 1965, as the scale of fighting increased, Portugal attempted to purchase 100 surplus Canadian built Sabre Mk 6s from West Germany, but instead, it was offered 40 G.91R/4s, which had originally been built for Greece and Turkey and which differed from the rest of the Luftwaffe G.91s sufficiently to create maintenance problems in exchange for allowing Germany to build and use an airbase at Beja in Portugal for training.