The first Summer Olympics after WWII took place in the

1. London returned the Olympics to the world

After the 1936 Berlin Games and the cancellation of the 1940 and 1944 Olympiads, the International Olympic movement reconvened in London in 1948; London became the second city to host the Summer Games twice and organized what contemporary accounts called the XIV Olympiad under severe postwar constraints ^{[1] [4]}.

2. "Austerity Games" — a label with detail and consequence

Contemporary and later accounts emphasize that the 1948 Games were deliberately frugal: no new major venues were built, athletes were housed in existing facilities, and Britain’s wartime rationing shaped the scale and atmosphere of the event — hence the enduring label "Austerity Games" applied by Life, the London Museum and historic overviews ^{[5] [2] [6]}.

3. Participation and symbolism: recovery, not normalcy

The 1948 Olympics brought together competitors from 59 nations and roughly 4,000 athletes — a significant return after a 12‑year gap — and were widely framed as a symbol of recovery and international cooperation even while political exclusions remained in place (Germany and Japan were not invited) ^{[2] [3] [7]}.

4. Firsts and innovations amid scarcity

Despite austerity, the London Games introduced technical and broadcasting milestones: they were the first Summer Olympics televised (to small local audiences), they used starting blocks in sprint races for the first time, and introduced Olympic pictograms for sports and ceremonies — innovations recorded by the IOC and contemporary reportage ^{[4] [1] [8]}.

5. Sporting highlights that shaped postwar Olympic memory

The 1948 edition produced memorable performances that entered sporting lore: Fanny Blankers‑Koen won four gold medals as a 30‑year‑old mother, Emil Zátopek won the 10,000 m, and young American Bob Mathias captured the decathlon at age 17 — achievements highlighted in retrospective accounts ^{[2] [5] [4]}.

6. Who was and wasn’t there — geopolitical aftershocks

Sources make clear that the Games reflected the political settlement of 1945: defeated Axis powers Germany and Japan were excluded; the Soviet Union did not participate although several communist countries attended; newly independent and colonial territories also appeared for the first time, underlining shifting global orders ^{[7] [3]}.

7. Why London hosted: infrastructure, history, and practicality

London was selected in part because existing facilities and organizational experience made it a practical choice during scarcity. The city had previously hosted in 1908, and organizers relied on pre‑war venues rather than new construction — a pragmatic answer to postwar realities noted across sources ^{[1] [9] [4]}.

8. Conflicting details and limits of available sources

Most sources agree on the core fact—London 1948 as the first post‑war Summer Olympics ^{[1] [3]}. Some user‑generated pages and study aids reproduce medal counts or participant totals with small numeric differences; official IOC and established historical summaries are the consistent authorities for formal counts and dates ^{[8] [10] [7]}. Available sources do not mention any alternative city hosting the first post‑war Summer Games.

9. What this tells us about sport and politics in 1948

The 1948 Games reveal sport’s dual role as both a restorative international ritual and a stage shaped by contemporary politics: recovery and camaraderie were foregrounded, but exclusions and emerging Cold War alignments were also evident in which countries were present and which were not ^{[7] [3]}.

10. Bottom line for the original query

The concise, verifiable answer is: the first Summer Olympics after World War II took place in London in 1948 — the XIV Olympiad, known as the Austerity Games — reuniting the world’s athletes after a 12‑year hiatus and leaving a legacy of pragmatic staging and notable athletic performances ^{[1] [2] [3]}.