W was invented in the 7th Ct. AD by Anglo Saxon writers, it was originally a double U (hence its English name).
Latin /w/ developed into Romance /v/, therefore, V no longer adequately represented Germanic /w/. In German – like in Romance – the phoneme /w/ was lost, this is why German W represents /v/ rather than /w/. In Dutch, W is an approximant (with the exception of words with –EEUW, which have [-e:w]).