  The Small Magellanic Cloud (SMC) is the host of a rich system of globular
clusters (GCs) that span a wide age range. The chemical composition of the SMC
clusters is still poorly understood, despite their significance to chemical
evolution studies. Here, we provide the first detailed chemical study of
evolved giants in three distinct clusters, NGC 121 (10.5 Gyr), NGC 339 (6 Gyr),
and NGC 419 (1.4 Gyr). Results are based on high-resolution spectra obtained
with FLAMES at the Very Large Telescope. The chemical fingerprints of these
clusters closely resemble those of SMC field stars, supporting the SMC's
specific history of chemical enrichment relative to the Milky Way. The
approximately solar-scaled [alpha/Fe] observed in all three clusters,
independent of their [Fe/H], demonstrate the SMC's low star formation
efficiency. Compared to their Milky Way counterparts, elements primarily
produced by massive stars are severely underrepresented. Particularly, the
young cluster NGC 419's extremely low [Zn/Fe] shows that hypernovae have
contributed relatively little during the past two Gyr. The three GCs have high
[Eu/Fe] values regardless of their age. This suggests that the production of
the r-process elements in the SMC was extremely efficient up to 1.5 Gyr ago,
with an enrichment timescale comparable to that from Type Ia supernovae. When
the properties of the oldest SMC object NGC 121 are compared to those of
in-situ Milky Way clusters and accreted clusters linked to the Gaia-Enceladus
merger event, it is shown that the SMC had already attained the same
metallicity as Gaia-Enceladus but with lower [Fe/H] ratios at the age of NGC
121. This suggests that the chemical enrichment histories of the early SMC and
Gaia-Enceladus differed, and that the SMC probably had a lower mass in its
early ages than Gaia-Enceladus.
