My native language is Croatian, I've studied English and German and English seems to be, in some cases, more similar to Croatian than to German. Here are some words to compare:
English-Croatian-German
be-biti-sein
stand (verb)-stati-stehen
water-voda-wasser
two-dva-zwei
three-tri-drei
seven-sedam-sieben
twenty-dvadeset (pronounced dwah-yeest)-zwanzig
am (1st person singular present of to be)-sam-bin
us (pronoun)-nas-uns
me (pronoun)-me-mich
mother-mater (archaic)-mutter
brother-brat-bruder
sister-sestra-schwester
rather (adverb)-radije-lieber
first-prvi-zuerst
grave-grob-grab
no-ne-nein
yes-je (3rd person singular present of biti)-ja
sun-sunce-sonne
tree-drvo-baum
day-dan-tag
night-noc-nacht
boat-brod-boot
home-dom-heim
live-ziv-leben
eat-jesti-essen
cow-krava-kuh
The correspondence seems to be even systematical: f in English corresponds to p in Croatian, th in English corresponds to t in Croatian, t in English corresponds to d in Croatian, i in English corresponds to e in Croatian (nine-devet, six-sest, five-pet), and so on.
Maybe some of the words I've listed don't share the same root, but just sound very similar.
As for the grammar, English is, for example, more similar to Croatian than to German in the way it creates the interrogative sentences. The verb do might correspond to the Croatian interrogative particle "Da li" (in the beginning of a sentence).
The definite article "the" may correspond to the Croatian demonstrative pronoun "ti" (these).
The indefinite articles "an" and "a" may correspond to the Croatian pronoun "jedan" (usually translated as "one").
I am not a professional linguist, and I don't have the knowledge or skills needed to evaluate my hypothesis, so, what are your thoughts on this?