The Nazis built a load of purpose built holiday accommodation blocks in the 1930s which I guess could be described as package holidays, although which blockade they'd be defeating is beyond me, they also weren't air tours.
Thomas Cook organised the first package holiday in the 1850s with an organised tour of Europe with the intention of educating his customers about the local traditions of each country - seems they've gone slightly off course in recent years though.
"Vladimir Raitz, the co-founder of the Horizon Holiday Group, pioneered the first mass package holidays abroad with charter flights between Gatwick airport and Corsica in 1950, and organised the first package holiday to Palma in 1952, Lourdes in 1953, and the Costa Brava and Sardinia in 1954. In addition, the amendments made in Montreal to the Convention on International Civil Aviation on June 14, 1954 was very liberal to Spain, allowing impetus for mass tourism using charter planes."
The above paragraph was taken from Wikipedia. The Chicage Covention was signed in 1944 and defined a number of rules and regulations for air travel, although again I don't know what blocakdes it was defeating, although with it being 1944 it would have to be something to do with the war.
The aims of the convention were as follows:
"WHEREAS the future development of international civil aviation can greatly help to create and preserve friendship and understanding among the nations and peoples of the world, yet its abuse can become a threat to the general security; and
WHEREAS it is desirable to avoid friction and to promote that co-operation between nations and peoples upon which the peace of the world depends;