  We present results from the XMM-Newton observations of our ongoing program on
merging clusters. To date three clusters have been observed, covering the
temporal sequence from early to late stage mergers: A1750, A2065 and A3921.
Using spatially-resolved spectroscopy of discrete regions, hardness ratio and
temperature maps, we show that all three clusters display a complex temperature
structure. In the case of A1750, a double cluster, we argue that the observed
temperature structure is not only related to the ongoing merger but also to
previous merger events. A2065 seems an excellent example of a `compact merger',
i.e. when the centres of the two clusters have just started to interact,
producing a shock in the ICM. Using comparisons with numerical simulations and
complementary optical data, the highly complex temperature structure evident in
A3921 is interpreted as an off-axis merger between two unequal mass components.
These results illustrate the complex physics of merger events. The relaxation
time can be larger than the typical time between merger events, so that the
present day morphology of clusters depends not only on on-going interaction but
also on the more ancient formation history.
